# December 2008, Volume 17, Number 4

**W. Tangsrirat**
[references] [full-text]

Electronically Tunable Multi-Terminal Floating Nullor and Its Applications

A realization scheme of an electronically tun- able multi-terminal floating nullor (ET-MTFN) is de- scribed in this paper. The proposed circuit mainly employs a transconductance amplifier, an improved translinear cell, two complementary current mirrors with variable current gain and improved Wilson current mirrors, which provide an electronic tuning of the current gain. The va- lidity of the performance of the scheme is verified through PSPICE simulation results. Example applications employing the proposed ET-MTFN as an active element demonstrate that the circuit properties can be varied by electronic means.

- SENANI, R. A novel application of four-terminal floating nullors. Proceedings of the IEEE, 1987, vol. 75, p. 1544-1546.
- HIGASHIMURA, M. Current-mode allpass filter using FTFN with grounded capacitor. Electronic Letters, 1991, vol. 27, p. 1182-1183.
- LIU, S. I. Cascasable current-mode filters using single FTFN. Electronic Letters, 1995, vol. 31, no. 23, p. 1965-1966.
- CHIPIPOP, B., SURAKAMPONTORN, W. Realisation of current- mode FTFN-based inverse filter. Electronic Letters, 1999, vol. 35, p. 690-692.
- BHAKAR, D. R. Ground-capacitor SRCO using only one PFTFN. Electronic Letters, 2002, vol. 38, no. 20, p. 1156-1157.
- HUIJSING, J. H., VEELENTURF, C. F. Monolithic class AB operational mirrored amplifier. Electronic Letters, 1981, vol. 17, p. 119-120.
- LAOPOULOS, T. H., SISKOS, S., BAFLEUR, M., GIVELIN, P. H., TOURNIER, E. Design and application of an easily integrable CMOS operational floating amplifier for the megahertz range. Analog Integrated Circuits and Signal Processing, 1995, vol. 7, p. 103-111.
- CAM, U., TOKER, A., KUNTMAN, H. CMOS FTFN realization based on translinear cells. Electronic Letters, 2000, vol. 36, p.1255- 1256.
- TANGSRIRAT, W., UNHAVANICH, S., DUMAWIPATA, T., SURAKAMPONTORN, W. FTFN with variable current gain. In Proceedings of IEEE Region 10 International Conference on Electrical and Electronic Technology (TENCON), 2001, vol. 1, p. 209-212.
- ARAYAWAT, TRISUWANNAWAT, T. Electronically tunable current gain FTFN using OTAs. In Proceedings of ICCAS 2005, Gyeonggi-Do (Korea), 2005.
- ABUELMA’ATTI, M. T., AL-ZAHER, H. A., AL-QAHTANI, M. A. Novel grounded-capacitor active biquads using FiTFN. Microelectronics Journal, 1998, p.123-132.
- KANETSUKI, N., HIGASHIMURA, M., BEPPU, T., TSUKUTANI, T., FUKUI, Y. A realization of biquadratic circuit using MO-CCIIs and capacitors. In Proceedings of the 2003 International Technical Conference on Circuits, Systems, Computers and Communications, Kang-Won Do (Korea), 2003, vol. 3, p. 1615-1618.
- GILBERT, B. Current-mode circuits from a translinear viewpoint : A tutorial”, in Analog IC Design : The Current-Mode Approach, TOUMAZOU, C., LIDGEY, F.J., and HAIGH, D.G., Eds. London, U.K. : Peter Peregrinus, 1990, p.11-91.
- FABRE, A., MIMECHE, N. Class A/AB second-generation current conveyor with controlled current gain. Electronic Letters, 1994, vol. 30, p. 1267-1268.
- FREY, D. R. Log-domain filter: an approach to current-mode filtering. IEE Proceedings, Pt. G., 1993, vol. 140, p. 406-416.
- SOLIMAN, A. M. Theorems relating to port interchange in current- mode CCII circuits. International Journal of Electronics, 1997, vol. 82, p. 585-604.

Keywords: Four-Terminal Floating Nullor (FTFN), Current Conveyor (CC), current-mode circuits.

**T. Sutory, Z. Kolka**
[references] [full-text]

Characterization of Nonlinear Integrated Capacitors

The paper deals with a modified CBCM (Charge-Based Capacitance Measurements) method for nonlinear capacitance characterization. The method is characterized by high resolution although it is based on equipment found in any average laboratory. CBCM was originally developed for linear interconnect measurements. The proposed modification uses two DC swept sources to measure the whole nonlinear Q-v characteristic in both polarities without the necessity to switch the measured object. A test-chip implementing the method was designed and manufactured in the 0.35μm CMOS process. Verifica- tion against known capacitances proved the correctness and accuracy of the method. It was successfully used for MOSCAPs characterization.

- KORTEKAAS, C. On-chip quasi-static floating-gate capacitance measurement method. In Proceedings of the IEEE International Conference on Microelectronic Test Structures. San Diego (USA), 1990, vol. 3, p. 109-113.
- LORIVAL, R., NOUET, P. A test chip for MOS transistor capacitance characterization. In Proceedings of the IEEE Int. Conference on Microelectronic Test Structure. Nara (Japan), 1995, vol. 8, p.139-144.
- SONG, H., DONS, E., SUN, X.Q., FARMER, K. R. Leakage compensated charge method for determining static C-V characteristics of ultra-thin MOS capacitors. In Proc. of the NIST Int. Conference on Characterization and Metrology for ULSI Technology. Gaithersburg (USA), 1998, p. 231-234.
- OHKAWA, S., AOKI, M., MASUDA, H. Analysis and characterization of device variations in an LSI chip using an integrated device matrix array. IEEE Transactions on Semiconductor Manufacturing, 2004, vol. 17, no. 2, p. 155 – 165.
- CHEN, J., SYLVESTER, D., HU, C. An on-chip, interconnect capacitance characterization cethod with sub-femto-farad resolution. IEEE Trans. on Semiconductor Manufacturing, 1998, vol. 11, no. 2, p. 204-210.
- CHANG, Y. W., CHANG, H. W., HSIEH, C. H., LAI, H. C., LU, T. C., TING, W., KU, J., LU, C. Y. A novel simple CBCM method free from charge injection-induced errors. IEEE Electron Device Letters, 2004, vol. 25, no 5, p. 262-264.
- CHANG, Y. W., CHANG, H. W., LU, T. C., KING, Y. C., TING, W., KU, J., LU, C. Y. Charge-based capacitance measurement for bias-dependent capacitance. IEEE Electron Device Letters, 2006, vol. 27, no. 5, p. 390-392.
- VENDRAME, L., BORTESI, L., BOGLIOLO, A. Accuracy assessment and improvement of on-chip charge-based capacitance measurements. In Proceedings of the 7th IEEE SPI Workshop, Siena (Italy), 2003.
- SHEU, B. J., HU, C. M. Modeling the switch-induced error voltage on a switched capacitor. IEEE Transaction on Circuit and Systems, 1983, vol. 30, no 12, p. 911-913.
- DING, Y., HARJANI, R. A universal analytic charge injection model. In Proceedings of ISCAS 2000, Geneva (Switzerland), 2000, p. I-144 – I-147.

Keywords: Charge-based capacitance measurements, structures, MOS capacitors, integrated circuits. test

**D. Biolek, R. Senani, V. Biolkova, Z. Kolka**
[references] [full-text]

Active Elements for Analog Signal Processing: Classification, Review, and New Proposals

In the paper, an analysis of the state-of-the-art of active elements for analog signal processing is presented which support – in contrast to the conventional operational amplifiers – not only the voltage-mode but also the current- and mixed-mode operations. Several problems are addressed which are associated with the utilization of these elements in linear applications, particularly in frequency filters. A methodology is proposed which generates a number of fundamentally new active elements with their potential utilization in various areas of signal processing.

- FERRI, G., GUERRINI, N.C. Low-Voltage Low-Power CMOS Current Conveyors. Cluwer Academic Publishers, 2003.
- TOUMAZOU, C., LIDGEY, F.J., HAIGH, D.G. Analogue IC Design: The current mode approach. IEE Circuits and Systems Series 2. Peter Peregrinus Ltd., 1990.
- SCHMID, H. Why ”Current Mode” does not guarantee good performance. Analog Integrated Circuits and Signal Processing, 2003, vol. 35, p. 79-90.
- SMITH, K.C., SEDRA, A. The current conveyor: a new circuit building block. IEEE Proc. CAS, 1968, vol. 56, no. 3, p. 1368-1369.
- SEDRA, A.S., SMITH, K.C. A second generation current conveyor and its application. IEEE Trans., 1970, CT-17, p. 132-134.
- FABRE, A. Third generation current conveyor: A new helpful active element. Electron. Lett., 1995, vol. 31, no. 5, p. 338–339.
- WADSWORTH, D.C. Accurate current conveyor topology and monolithic implementation. Proc. IEE G, 1990, vol. 137, no. 2, p. 88-94.
- SVOBODA, J.A, Mc GORY, L., WEBB, S. Application of commercially available current conveyors. International Journal of Electronics, 1991, p. 159-164.
- WILSON, B. Recent developments in current conveyors and currentmode circuits. IEE Proc. G, 1990, vol. 132, p. 63-76.
- IKEDA, K., TOMITA, Y. Realization of current-mode biquadratic filter using CCIIs with current followers. Electron. Commun. Jpn. Pt. 2, Electron., 1991, vol. 71, no. 5, p. 809-815.
- ELWAN, H.O., SOLIMAN, A.M. Novel CMOS differential voltage current conveyor and its applications. IEE Proceedings: Circuits, Devices and Systems, 1997, vol. 144, no. 3, p. 195–2007.
- AWAD, I. A., SOLIMAN, A. M. Inverting second generation current conveyors: the missing building blocks, CMOS realizations and applications. International Journal of Electronics, 1999, vol. 86, no. 4, p. 413–432.
- CHIU, W., LIU, S.I., TSAO, H.W., CHEN, J.J. CMOS differential difference current conveyors and their applications. IEE Proc., Circuits, Devices, Syst., 1996, vol. 143, no. 2, p. 91–96.
- GUPTA, S. S., SENANI, R. Comments on “CMOS differential difference current conveyors and their applications”. IEE Proc. Circuits, Devices and Systems, 2001, vol. 148, p. 335–336.
- ELWAN, H.O., SOLIMAN, A.M. CMOS differential current conveyors and applications for analog VLSI. Analog Integrated Circuits and Signal Processing, 1996, vol. 11, p. 35-45.
- ZEKI, A., TOKER, A. The dual-X current conveyor (DXCCII): A new active device for tunable continuous-time filters. Int J Electron., 2002, vol. 89, p. 913-923.
- SOLIMAN, A.M. New fully-differential CMOS second-generation current conveyer. ETRI Journal, 2006, vol, 28, no. 4, p. 495-501.
- HWANG, Y.-S., LIN, J-F., WU, H-Y, CHEN, J-J. A new FBCCIIbased Pipelined ADC. In Conference on Innovative Applications of System Prototyping and Circuits Design. Taiwan, 2007, p. 16.
- DUKIC, S. The analysis of full-wave wide-band precision rectifier with modified second type current conveyor. Facta Universitatis (NIS), Ser.: Elec. Energ., 2007, vol. 20, no. 2, p. 215-221.
- TOUMAZOU, C., PAYNE, A. operational floating conveyor. Electronics Letters, 1991, vol. 27, no. 8, p. 651-652.
- BECVAR, D., VRBA, K., ZEMAN, V., MUSIL, V. Novel universal active block: a universal current conveyor. In Proc. of the IEEE Int. Symp. on CAS. Geneva (Switzerland), vol. 3, 2000. p. 471-473.
- KUNTMAN, H., CICEKOGLU, O., OZOGUZ, S. A modified third generation current conveyor, its characterization and applications. Frequenz, 2002, vol.56, p. 47-54.
- GIFT, S.J.G. Hybrid current-conveyor-operational amplifier circuit. Int. J. Electronics, 2001, vol. 88, no. 12, p. 1225-1235.
- FABRE, A., SAAID, O., WIEST, F., BOUCHERON, C. Currentcontrolled bandpass filter based on translinear conveyor. Electron. Lett., 1995, vol. 31, no. 20, p. 1727-1728.
- FABRE, A., SAAID, O., WIEST, F., BOUCHERON, C. High frequency applications based on a new current-controlled conveyor. IEEE Trans. Circuits Syst. I, 1996, vol. 43, no. 2, p. 82-91.
- BARTHELEMY, H., FABRE, A. A second generation currentcontrolled conveyor with negative intrinsic resistance. IEEE Trans. Circuits Syst. I, 2002, vol. 49, no. 1, p. 63–65.
- SENANI, R., SINGH, V.K., SINGH, A.K., BHASKAR, D.R. Novel electronically controllable current-mode universal biquad filter. IEICE Electronics Express, 2004, vol. 1, no. 14, p. 410-415.
- EL2082 – Current-Mode Multiplier. http://www.datasheet4u.com/html/E/L/2/EL2082_ElantecSemicon ductor.pdf.html
- ABUELMA’ATTI, M.T., KHALAF, A.A-A., ABDULSHAKOOR, A. Programmable second-generation current-conveyor with variable current gain. Active and Passive Elec. Comp., 1995, vol. 17, p. 257- 260.
- ALZAHER, H.A. CMOS digitally programmable quadrature oscillators. Int. J. Circ. Theor.Appl., 2008. Published online in Wiley InterScience.
- EE times Design Classic Series, “Unsung hero pioneered Op-amps”, retrievable at http://www.eetimes.com/anniversary/designclassics/opamp.html.
- GAP/R - George A. Philbrick Researches Archive. www.PhilbrickArchive.org
- CARLIN, H. Singular network element. IRE Trans. Circuit Theory, 1964, vol. CT-11, p. 67-72.
- SCHMID, H. Approximating the universal active element. IEEE Trans. Circuits Syst. II, 2000, vol. 47, no. 11, p. 1160-1169.
- SACKINGER, E., GUGGENBIIHL, W. A versatile building block: The CMOS differential difference amplifier. IEEE J. Solid-State Circuits, 1987, vol. SC-22, p. 287-294.
- HUANG, S-C., ISMAIL, M., ZARABADI, S.R. A wide range Differential Difference Amplifier: A basic block for analog signal processing in MOS technology. IEEE Trans. Circuits Syst. II, 1993, vol. 40, no. 5, p. 289-301.
- HUIJSING, J. H., De KROTE, J. Monolithic Nullor – a universal active network element. IEEE Journals of Solid-State Circuits, 1977, vol. SC-12, p. 59-64.
- TELLEGEN, B.D.H. La recherche pour une serie complete delements de circuits indeaux nonlineaires. Rendicoti Semin. Mat. Fis., Milan (Italy), 1954, vol. 25, p. 134-144.
- NORDHOLT, E.H. Extending op-amp capabilities by using currentsource power supplies. IEEE Trans. Circuits Syst., 1982, vol. CAS- 29, no. 6, p. 411-414.
- SENANI, R. A novel application of four-terminal floating nullors. Proc. of the IEEE, 1987, vol. 75, no. 11, p. 1544-1546.
- HUIJSING, J. H. Operational floating amplifier. IEE Proceedings, 1990, vol. 137, Pt.G, no. 2, p. 131-136.
- CHIPIPOP, B., SURAKAMPORNTORN, W. Realisation of currentmode FTFN-based inverse filter. El. Lett., 1999, vol. 35, p. 690-692.
- ABUELMA’ATI, M.T., Al-ZAHER, H. A. Universal two-input current-mode active biquad using FTFNs. Int. Journal of Electronics, 1999, vol. 86, p. 181-188.
- HUIJSING, H. J., VEELENTURF, C.F. Monolitic class AB operational mirrored amplifier. El. Lett., 1981, vol. 17, p. 119-120.
- BHASKAR, D.R. Grounded-capacitor SRCO using only one PFTFN. El. Lett., 2002, vol. 38, no. 20, p. 1156-1157.
- ABUELMA’ATI, M.T., Al-ZAHER, H. A., Al-QUAHTANI, M. A. Novel grounded-capacitor active biquads using FiTFN. Microelectronics Journal, 1998, vol. 86, p. 123-132.
- JIRASERI-AMORNKUN, A., SURAKAMPONTORN, W. Constant-gm Rail-to-Rail CMOS Multi-Output FTFN. In Proc. of the 2002 Int. Tech. Conf. on Circuits/Systems, Computers and Communications. Phuket (Thailand), 2002, p. 333-336.
- JIRASERI-AMORNKUN, A., CHIPIPOP, B., SURAKAMPONTORN, W. Novel translinear-based multi-output FTFN. In Proc. of 2001 IEEE Int. Symp. on Circuits and Systems. Sydney (Australia), 2001, I-180- I-183.
- TANGSRIRAT, W., UNHAVANICE, S., DUMAWIPATA, T., SURAKAMPONTORN, W. FTFN with Variable Current Gain. Proc. of IEEE Region 10 Int. Conf. on Electrical and Electronic Technology (TENCON), vol. 1. Thailand, 2001, p. 209-212.
- ARAYAWAT, S., CHAIKLA, A., RIEWRUJA, V., TRISUWANNAWAT, T. Electronically Tunable Current Gain FTFN Using OTAs. In Proc. of ICCAS 2005. Kintex, Gyeonggi-Do (Korea), 2005.
- MAHMOUD S.A., SOLIMAN A.M. The Differential Difference Operational Floating Amplifier: A new block for analog signal processing in MOS technology. IEEE Trans. On CAS – II, 1998, vol. 45, no. 1, p. 148-158.
- ALZAHER, H., ISMAIL, M. A CMOS Fully Balanced Four- Terminal Floating Nullor. IEEE Trans. On CAS – I, 2002, vol. 49, no. 4, p. 413-424.
- KUMAR, P., SENANI, R. Bibliography on Nullors and their applications in Circuit Analysis Synthesis and Design. Analog Integrated Circuits and Signal Processing, 2002, vol. 33, p. 65-76.
- DELIYANNIS, T., SUN, Y., FIDLER, J.K. Continuous-Time Active Filter Design. CRC Press, USA, 1999.
- CHANG, C.-M., PAI, S.-K. Universal current-mode OTA-C biquad with the minimum components. IEEE Trans. Circuits Syst. 2000, vol. 47, no. 8, p. 1235-1238.
- ABUELMA'ATTI, M. T., BENTRCIA, A. New universal currentmode multiple-input multiple-output OTA-C filter. In Proc. of the 2004 IEEE Asia-Pacific Conf. on CAS. 2004, p. 1037-1040.
- BIOLEK, D., BIOLKOVA, V., KOLKA, Z. Universal current-mode OTA-C KHN biquad. In Proc. of the Int. Conf. ICECS 2007, Venice (Italy), 2007, p. 289-292.
- SENANI, R. Realisation of a class of analog signal processing/signal generation circuits: novel configurations using current feedback opamps. Frequenz, 1998, vol. 52, no. 9/10, p. 196-206.
- PALOUDA, H. National Semiconductors, Current Feedback amplifiers. Application Note 597. 1989, p. 1-10.
- SIRIPRUCHYANUN, M., CHANAPROMMA, C., SILAPAN, P., JAIKLA, W. BiCMOS current-controlled current feedback amplifier (CC-CFA) and its applications. WSEAS Trans. on Electronics, Special Issue “Modern Circuit Components for Analogue Signal Processing and Their Applications”, to be issued in 2008.
- GUNES, E.O., TOKER, A. On the realization of oscillators using state equations. Int. J. Electron. Commun. (AEU), 2002, vol. 56, no. 5, p. 1-10.
- GUPTA, S.S., SENANI, R Grounded-capacitor SRCOs using a single differential difference complementary current feedback amplifier. IEE Proc.-Circ Dev Syst., 2005, vol. 152, no. 1, p. 38-48.
- KAULGERG, T. A CMOS Current-Mode Operational Amplifier. Int. Journal of Solid-State Circuits, 1993, vol. 28, no. 7, p. 849-852.
- MUCHA, I. Towards a true current operational amplifier. In Proc. of ISCAS’94. London (England), vol. 5, 1994, p. 389-392.
- BRUUN, E. A differential-input, differential-output current mode operational amplifier. Int. J. Electronics, 1991, vol. 71, no. 6, p. 1047-1056.
- SCHMID, H. The Current-Feedback OTA. In Proc. of the 2001 IEEE Int. Symp. on Circuits and Systems, ISCAS 2001. Sydney (Australia), vol. 1, 2001, p. 655 – 658.
- GIFT, S. J. G. An enhanced current-mode instrumentation amplifier. IEEE Trans. on Instr. Meas., 2001, vol. 50, no. 1, p. 85-88.
- GIFT, S. J. G. Balanced-output signal generator. IEEE Trans. on Instr. Meas., 2006, vol. 55, no. 3, p. 835-838.
- PAL, K. All pass/notch filters using operational amplifier and current conveyors. J. of Active and Passive Electronic Device, 2005, vol. 1, p. 289-294.
- GIFT, S.J.G. An improved precision full-wave rectifier. Int. J. Electronics, 2002, vol. 89, no. 3, p. 259-265.
- CHEN, J.J., TSAO, H.W., CHEN, C. Operational transresistance amplifier using CMOS technology. Electronics Letters, 1992, vol. 28, no. 22, p. 2087-2088.
- ACAR, C., OZOGUZ, S. A new versatile building block: current differencing buffered amplifier. Microelectronics Journal, 1999, vol. 30, p. 157-160.
- SALAMA, K.N., ELWAN, H.O., SOLIMAN, A.M. Parasiticcapacitance- insensitive voltage-mode MOSFET-C filters using differential current voltage conveyor. Circuits Systems Signal Process., 2001, vol. 20, no. 1, p. 1-16.
- KESKIN, A.U. A four quadrant analog multiplier employing single CDBA. Analog Integrated Circuits and Signal Processing, 2004, vol 40, p. 99-101.
- KESKIN, A.U. Design of a PID controller circuit employing CDBAs. International Journal of Electrical Engineering Education (Manchester, England), 2006, vol.43, p. 48-56.
- KESKIN, A.U., AYDIN, C., HANCIOGLU, E., ACAR, C. Quadrature oscillators using Current Differencing Buffered Amplifiers. Frequenz, 2006, vol.60, no. 3-4, p. 57-59.
- HORNG, J.W. Current differencing buffered amplifiers based single resistance controlled quadrature oscillator employing grounded capacitors. IEICE Trans. Fundamental, 2002, vol. E85-A, no.2, p. 1416- 1419.
- KLAHAN, K., TANGSRIRAT, W., SURAKAMPONTORN, W. Realization of multiphase sinusoidal oscillator using CDBAs Circuits and Systems. In Proceedings of the 2004 IEEE Asia-Pacific Conference. Taiwan, 2004, vol. 2, p. 725 – 728.
- BIOLEK, D., BIOLKOVA, V. SFG Simulation of General Ladder Filters Using CDBAs. In Proceedings of the ECCTD03. Krakow (Poland), 2003, vol. I, p. 385-388.
- BIOLEK, D., OLSAK, M., BIOLKOVA, V. Optimization of elliptic leap-frog CDBA-based filters. Contribution to the book "Computational Methods in Circuits and Systems Applications", WSEAS Press, Electrical and Computer Engineering Series, 2003, p. 221-225.
- MAHESHWARI, S., KHAN, I.A. Current-controlled current differencing buffered amplier: implementation and applications. Active and Passive Electron Components, 2004, vol. 27, p. 219-227.
- TANGSRIRAT, W., PRASERTSOM, D., SURAKAMPONTORN, W. Low-voltage digitally controlled current differencing buffered amplifier and its application. Int. J. Electron. Commun. (AEU), 2008, doi: 10.1016/j.aeue.2008.01.006.
- BIOLEK, D. CDTA – Building Block for Current-Mode Analog Signal Processing. In Proceedings of the ECCTD03. Krakow (Poland), 2003, vol. III, p. 397-400.
- TANGSRIRAT, W., SURAKAMPONTORN, W. Systematic realization of cascadable current-mode filters using current differencing transconductance amplifiers. Frequenz, 2006, vol. 60, no. 11-12, p. 241-245.
- SHAH, N.A., QUADRI, M., IQBAL, S.Z. CDTA based universal transadmittance filter. Analog Integr. Circ. Sig. Process. Journal, 2007, p. 65-69.
- SHAH, N.A., QUADRI, M., IQBAL, S.Z. Current-mode multifunction filter using current differencing transconductance amplifier. Indian Journal of Pure & Applied Physics, 2007, vol. 45, no. 9, p. 767-769.
- SHAH, N.A., QUADRI, M., IQBAL, S.Z. Electronically tunable transadmittance BP filter. Electronics World, 2007, p. 51-52.
- UYGUR, A., KUNTMAN, H. Seventh-order elliptic video filter with 0.1 dB pass band ripple employing CMOS CDTAs. Int. J. Electron. Commun. (AEU), 2007, vol. 61, no. 5, p. 320-328.
- TANGSRIRAT, W., DUMAWIPATA, T., SURAKAMPONTORN, W. Multiple-input single-output current-mode multifunction filter using current differencing transconductance amplifiers. Int. J. Electron. Commun. (AEU), 2007, vol. 61, no. 4, p. 209-214.
- UYGUR, A., KUNTMAN, H., ZEKI, A. Multi-input multi-output CDTA-based KHN filter. In Proc. of the 4th Int. Conf. on Electrical and Electronics ELECO 2005. Bursa (Turkey), 2005, p. 46-50.
- UYGUR, A., KUNTMAN, H. Low-voltage current differencing transconductance amplifier in a novel allpass configuration. In Proc. of the 13th IEEE Mediterranean Electrotechnical Conference MELECON'06, Spain, 2006, p. 23-26.
- TANJAROEN, W, DUMAWIPATA, T., UNHAVANICH, S., TANGSRIRAT, W., SURAKAMPONTORN, W. Design of current differencing transconductance amplifier and its application to current-mode KHN biquad filter. In Proc. of the ECTI-CON 2006, Thailand, 2006.
- TANGSRIRAT, W., TANJAROEN, W. Current-Mode Multiphase Sinusoidal Oscillator Using Current Differencing Transconductance Amplifiers. Circuits Syst Signal Process., 2008, vol. 27, p. 81-93.
- TANGSRIRAT, W. Current differencing transconductance amplifier-based current-mode four-phase quadrature oscillator. Indian Journal of Engineering&Materials Sciences, 2007, vol. 14, p. 289-294.
- KESKIN, A.U., BIOLEK, D. Current mode quadrature oscillator using current differencing transconductance amplifiers (CDTA). IEE Proceedings - Circuits, Devices and Systems, 2006, vol. 153, no. 3, p. 214 - 218.
- KESKIN, A.U., BIOLEK, D., HANCIOGLU, E., BIOLKOVA, V. Current-mode KHN filter employing current differencing transconductance amplifiers. Int. J. Electron. Commun. (AEU), 2006, vol. 60, no. 6, p. 443-446.
- BIOLEK, D., HANCIOGLU, E., KESKIN, A.U. High-performance current differencing transconductance amplifier and its application in precision current-mode rectification. Int. J. Electron. Commun. (AEU), 2008, vol. 62, no. 2, p. 92-96.
- PROKOP, R., MUSIL, V. New modular current devices for true current mode signal processing. Electronics, 2007, vol. 16, no. 4, p. 36-42.
- SIRIPRUCHYANUN, M., JAIKLA, W. CMOS current-controlled current differencing transconductance amplifier and applications to analog signal processing. Int. J. Electron. Commun. (AEU), 2008, vol. 62, no. 4, p. 277-287.
- SIRIPRUCHYANUN, M., JAIKLA, W. A current-mode analog multiplier/divider based on CCCDTA. Int. J. Electron. Commun. (AEU), 2008, vol. 62, no. 3, p. 223-227.
- SIRIPRUCHYANUN, M., JAIKLA, W., Realization of current controlled current differencing transconductance amplifier (CCCDTA) and its applications. Transactions on Electrical Eng., Electronics, and Communications ECTI-EEC, 2007, vol. 5, no.1, p. 41-50.
- JERABEK, J., VRBA, K. Filters based on active elements with current mirrors and inverters. GESTS International Trans. on Communication and Signal Processing, 2006, vol. 8, no. 1.
- TILIUTE, D.E. Full-wave current-mode precision rectifiers using unity-gain cells. Elektronika ir Elektrotechnika, 2003, vol. 49, no. 7, p. 26-29.
- BIOLEK, D., GUBEK, T. New circuit elements for current-mode signal processing. Elektrorevue, 2004/28. [online]. Available at: http://www.elektrorevue.cz. Cited 2004-05-03.
- PROKOP, R., MUSIL, V. New modern circuit block CCTA and some its applications. In Proc. of the Fourteenth International Scientific and Applied Science Conference—Electronics ET’2005. Sofia (Bulgaria), 2005, p. 93–98.
- SIRIPRUCHYANUN, M., JAIKLA, W. Current controlled current conveyor transconductance amplifier (CCCCTA): a building block for analog signal processing. Electr Eng, 2008, vol. 90, p. 443-453.
- VAVRA, J, BIOLEK, D. Grounded impedance current sensing. In Proc. EDS’08 IMAPS CS Int. Conference. Brno (Czech Republic), 2008, p. 13-18.
- CICEKOGLU, O., TARIM, N., KUNTMAN, H. Wide dynamic range high output impedance current-mode multifunction filters with dual-output current conveyors. Int. J. Electron. Commun. (AEU), 2002, vol. 56, no. 1, p. 55-60.
- TSUKUTANI, T., SUMI, Y., YABUKI, N. Novel current-mode biquadratic circuit using only plus type DO-DVCCs and grounded passive components. Int. Journal of Electronics, 2007, vol. 94, p. 1137-1146.
- MAX435/436 Wideband Transconductance Amplifiers. Datasheet, 19-0042, Rev. 1, 4/93. Maxim Integrated Products.

Keywords: Active element, current conveyor, operational amplifier, OTA, CDBA, CDTA, filter.

**W. Jaikla, M. Siripruchyanun, J. Bajer, D. Biolek**
[references] [full-text]

A Simple Current-Mode Quadrature Oscillator Using Single CDTA

This article presents a simple current-mode quadrature oscillator using a single Current Differencing Transconductance Amplifier (CDTA) as the active element. The oscillation condition and oscillation frequency can be electronically controlled. The circuit structure is very simple, consisting of merely one CDTA, one resistor and two capacitors. The proposed circuit is suitable for IC architecture. The PSpice simulation and experimental results are shown, and the results agree well with the theoretical assumptions.

- KHAN, I. A., KHAWAJA, S. An integrable gm-C quadrature oscillator. International Journal of Electronics, 2000, vol. 87, no. 1, p. 1353-1357.
- TOUMAZOU, C., LIDGEY, F. J., HAIGH, D. G. Analogue IC Design: The Current-Mode Approach. London: Peter Peregrinus, 1990.
- BIOLEK, D. CDTA – Building block for current-mode analog signal processing. In Proceedings of the European Conference on Circuit Theory and Design 2003. Krakow (Poland), 2003, p. 397–400.
- BIOLEK, D. BIOLKOVA, V. Universal biquads using CDTA elements for cascade filter design. In Proceeding of the 13th International Multiconference on Circuits, Systems, Communications & Computers (CSCC2003). Corfu (Greece), 2003, p. 8–12.
- SIRIPRUCHYANUN, M., JAIKLA, W. Realization of current controlled current differencing transconductance amplifier (CCCDTA) and its applications. ECTI Trans. on Electrical Engineering, Electronics, and Communications. 2007, vol. 5, no. 1, p. 41-50.
- BIOLEK, D., BIOLKOVA, V., KOLKA, Z. Single-CDTA (Current Differencing Transconductance Amplifoer) current-mode biquad revisited. WSEAS Trans. on Electronics, Special Issue Modern Circuit Components for Analogue Signal Processing and their Applications. To be issued in 2008.
- JAIKLA, W., SIRIPRUCHYANUN, M. A versatile quadrature oscillator and universal biquad filter using dual-output current controlled current differencing transconductance amplifier. In Proc. of the International Symposium on Communications and Information Technologies 2006. Bangkok (Thailand), 2006, p. 1072-1075.
- BIOLEK, D., KESKIN, A. U., BIOLKOVA, V. Quadrature oscillator using CDTA-based integrators. WSEAS Transactions on Electronics, 2006, vol. 3, no. 9, p. 463-469.
- JAIKLA, W., SIRIPRUCHYANUN, M. CCCDTAs-based versatile quadrature oscillator and universal biquad filter. In Proceedings of ECTI conference 2007, Chieng Rai (Thailand), 2007, p. 1065-1068.
- KESKIN, A. U., BIOLEK, D. Current mode quadrature oscillator using current differencing transconductance amplifiers (CDTA). IEE Proceedings-Circuits, Devices and Systems. 2003, vol. 153, no. 3, p. 214–218.
- BIOLEK, D. BIOLKOVA, V., KESKIN, A. U. Current mode quadrature oscillator using two CDTAs and two grounded capacitors. In Proceedings of the 5th WSEAS International Conference on System Science and Simulation in Engineering, Tenerife, Canary Islands (Spain), 2006, p. 368-370.
- TANGSRIRAT, W., TANJAROEN, W. Current-mode multiphase sinusoidal oscillator using current differencing transconductance amplifiers. Circuits Systems and Signal Processing, 2008, vol. 27, p. 81–93.
- TANGSRIRAT, W., TANJAROEN, W., PUKKALANUN, T. Current-mode multiphase sinusoidal oscillator using CDTA-based allpass sections. International Journal of Electronics and Communications (AEU). 2008, online first.
- PROKOP, R., MUSIL, V. New modular current devices for true current mode signal processing. Electronics, 2007, vol. 16, no. 4, p. 36-42.
- KOLKA, Z., BIOLEK, D. BIOLKOVA, V. Symbolic analysis of linear circuits with modern active elements. WSEAS Trans. on Electronics, Special Issue Modern Circuit Components for Analogue Signal Processing and their Applications. To be issued in 2008.
- BAJER, J. CDTA applications for analog signal processing. Diploma work, Faculty of Military Technologies, University of Defense, Czech Republic, 2008, p. 65 (in Czech).
- FOREJTEK, J. Measuring the CDTA and CCTA chip. Research report for the Grant Agency of the Czech Republic, grant No. 102/05/0277, 2007 (in Czech).

Keywords: Oscillator, CDTA, current-mode

**P. Horsky**
[references] [full-text]

A Monotonic Precise Current DAC for Sensor Applications

In this paper a 17 bit monotonic precise current DAC for sensor applications is described. It is working in a harsh automotive environment in a wide temperature range with high output voltage swing and low current consumption. To guarantee monotonicity current division and segmentation techniques are used. To improve the output impedance, the accuracy and the voltage compliance of the DAC, two active cascoding loops and one follower loop are used. The resolution of the DAC is further increased by applying pulse width modulation to one fine LSB current. To achieve low power consumption unused coarse current sources are switched off. Several second order technological effects influencing final performance and circuits dealing with them are discussed.

- SCHOUWENAARS, H. J. et al. A low-power stereo 16-bit CMOS D/A converter for digital audio. IEEE J. Solid-State Circuits, Dec. 1988, vol. 23, no. 6, p. 1290 – 1297.
- DGROENEWELD, W. J. et al. A self-calibration technique for monotonic high resolution D/A converters. IEEE J. Solid-State Circuits, Dec. 1989, vol. 24, no. 6, p. 1517 – 1522.
- SCHOEFF, J. A. An inherently monotonic 12 bit DAC. IEEE J. Solid-State Circuits, Dec. 1979, vol. SC-14, no. 6, p. 904 – 911.
- MIKI, T. et al. An 80-MHz 8-bit CMOS D/A converter. IEEE J. Solid-State Circuits, Dec. 1986, vol. SC-21, no. 6, p. 904 – 911.
- TUINHOUT, H. P., PELGROM, M., DE VRIES, R. P., VERTREGT, M. Effects of metal coverage on MOSFET matching. In Technical Digest of the IEEE International Electron Device Meeting 1996, p. 735-738.
- VAN DE PLASSCHE, R. J. CMOS Integrated Analog-to-Digital and Digital-to-Analog Converters. 2nd edition Springer, 2003.

Keywords: Digital to analog converter, current output, segmentation, pulse width modulation, cascoding

**L. Dolivka, J. Hospodka**
[references] [full-text]

Ways to Optimize Analogue Switched Circuits

This paper describes how analogue switched circuits (switched-capacitor and switched-current circuits) can be optimized by means of a personal computer. The optimization of this kind of circuits is not so common and their analysis is more difficult in comparison with continuously working circuits. Firstly, the nonidealities occurring in these circuits whose effect on their characteristics should be optimized are discussed. Then a few ways to analyze analogue switched circuits are shown. From all optimization algorithms applicable for this kind of optimization, two ones that seem to be the most promising are proposed. The differential evolution (one of evolutionary algorithms) combined with the simplex method was found to be most appropriate from these two ones. Two types of programs are required for the optimization of these circuits: a program for implementing calculations of the used optimization algorithm and a program for the analysis of the optimized circuit. Several suitable computer programs from both of the groups together with their proper settings according to authors’ experience are proposed. At the end of the paper, an example of a switched-current circuit optimization documenting the previous description is presented.

- MARIK, V., STEPANKOVA, O., LAZANSKY, J. et al. Artificial Intelligence (in Czech), vol. 1, 2, 3, 4, and 5. Prague: Academia, 1993, 1997, 2001, 2003, and 2007, ISBN 80-200-0496-3, 80-200-0504-8, 80-200-0472-6, 80-200-1044-0, and 80-200-1470-5.
- ZELINKA, I. Artificial Intelligence in Global Optimization Problems (in Czech). Prague: BEN, 2002, ISBN 80-7300-069-5.
- KOSTKA, P., SKVOR, Z. Microwave-circuit optimization with parallel enhanced fast messy genetic algorithm (pefmGA). Radioengineering, vol. 12, no. 2, pp. 10–15. Brno: 2003, ISSN 1210-2512.
- DOLIVKA, L., HOSPODKA, J. Using the differential evolution algorithm for the multi-objective optimization of a switched-current circuit. In Proceedings of 2007 IEEE Congress on Evolutionary Computation (CD-ROM), pp. 1351–1358. IEEE, 2007, ISBN 1-4244-1340-0.
- ERTEN, I. G., DUNDAR, G., BALKIR, S. Optimization and synthesis of switched current filters with nonideal MOS transistors. In Proceedings of Third International Workshop on Design of Mixed-Mode Integrated Circuits and Applications 1999, pp. 13–17. 1999, ISBN 0-7803-5588-1.
- ANANDA MOHAN, P. V., RAMACHANDRAN, V., SWAMY, M. N. S. Switched Capacitor Filters – Theory, Analysis and Design. Prentice Hall International, 1995, ISBN 0-13-879818-4.
- TOUMAZOU, C., HUGHES, J. B., BATTERSBY, N. C. Switched-Currents: An Analogue Technique for Digital Technology. London: Peter Peregrinus Ltd., 1993, ISBN 0-86341-294-7.
- BIOLEK, D., BIOLKOVA, V., KOLKA, Z. AC analysis of switched-capacitor filters in Spice. In Proceedings of NSSS IX. (CD-ROM), pp. 50–55. Liptovsky Mikulas: Military Academy, 2008, ISBN 978-80-8040-344-7.
- YUAN, F., OPAL, A. Computer methods for switched circuits. IEEE Transactions on Circuits and Systems I, 2003, vol. 50, no. 8, pp. 1013–1024. IEEE, ISSN 1057-7122.
- BICAK, J., HOSPODKA, J. Frequency response of switched circuits in SPICE. In Proceedings of ECCTD’03, pp. I-333–I-336. Krakow: IEEE, 2003, ISBN 83-88309-95-1.
- BICAK, J., HOSPODKA, J. Using WinSpice program for switched-capacitor filter analysis. WSEAS Transactions on Circuits and Systems, 2005, vol. 8, no. 4, pp. 992–1001. ISSN 1109-2734.
- BIOLEK, D. Modeling of periodically switched networks by mixed s-z description. IEEE Transactions on Circuits and Systems I, 1997, vol. 44, no. 8, pp. 750–758. IEEE, ISSN 1057-7122.
- BICAK, J., HOSPODKA, J. PraSCAn – Maple package for analysis of real periodically switched circuits. In Proceedings of Maple Conference 2005, pp. 8–18. Waterloo Ontario: Maplesoft, a division of Waterloo Maple, Inc., ISBN 1-894511-85-9.
- FERNANDEZ, F. V., RODRIGUEZ-VAZQUEZ, A., HUERTAS, J. L., GIELEN, G. G. E. Symbolic Analysis Techniques. New York: IEEE Press, 1998, ISBN 0-7803-1075-6.
- STORN, R., PRICE, K. Differential evolution – a simple and efficient heuristic for global optimization over continuous spaces. Journal of Global Optimization, 1997, vol. 11, no. 4, pp. 341–359. Kluwer Academic Publishers, ISSN 0925-5001.
- NELDER, J. A., MEAD, R. A simplex method for function minimization. Computer Journal, 1965, vol. 7, no. 4, pp. 308–313.
- DOLIVKA, L., HOSPODKA, J. Using various evolutionary algorithms for the optimization of analogue switched circuits. In Proceedings of NSSS IX. (CD-ROM), pp. 68–73. Liptovsky Mikulas: Military Academy, 2008, ISBN 978-80-8040-344-7.
- PINTER, J. D. Global Optimization in Action. Kluwer Academic Publishers, 1996. ISBN 0-7923-3757-3.
- Waterloo Maple, Inc.: http://www.maplesoft.com.
- MathWorks, Inc.: http://www.mathworks.com.
- SMITH M. WinSpice User’s Manual. http://www.winspice.com.
- Mentor Graphics Corp.: http://www.mentor.com.
- Cadence Design Systems, Inc.: http://www.cadence.com.

Keywords: Optimization, switched-capacitor circuit, switched-current circuit, evolutionary algorithm.

**O. Panagiev**
[references] [full-text]

Adaptive Compensation of the Nonlinear Distortions in Optical Transmitters Using Predistortion

The described method refers to compensation of nonlinear distortions, originating in laser diodes, used in wideband SCM-communication systems. Its essence is presenting in forming of a function that is opposite of the function describing the W-A characteristic of the emitting diode. Main element is the predistorter, which is connected in series before the emitting diode. This way, an improving of the optical transmitter’s parameters and characteristics is being realized, by using a purposive entering predistortion.

- WILLEMS, F., MUYS, W., VAN DER PLAATS, J. C., NUYTS, R. Experimental verification of self-phase-modulation induced nonlinear distortion in externally modulated AM-VSB Lightwave systems. Electron. Letters, 1996, vol. 32, no. 14, p.1310 - 1311.
- HELMS, J. Intermodulation distortions of broadband modulated laser diodes. J. L. Technology, 1992, vol.10, no.12, p. 1901-1906.
- PAN, Q., GREEN, R. Amplitude density of infrequent clipping impulse noise and Bit-Error Rate impairment in AM-VSB/M-QAM hybrid lightwave systems. IEEE Trans. Communications, 1996, vol. 44, no. 10, p. 1329-1334.
- PANAGIEV, O. Some capabilities of the optical technologies in the cable television systems. In Proceedings of the ІХ NSASC “Electronics'2000”. Sozopol (Bulgaria), 2000, p.163 - 170.
- ZEPPARELLI, F. Modelling and design of a broadband predistortion circuit for radio-over fiber systems. IEICE Tr. on Electronics, 2003, vol. E85-C, no. 3, p. 519 - 526.
- COX III, C. Analog optical links theory and practice. Cambridge University pres., 2004.
- SEO, J. H., SEO, Y. K., CHOI, W. Y. Nonlinear distortion suppression in directly modulated DFB lasers by sidemode optical injection. IEEE MTT-S Digest, 2001, p. 555 - 558.
- GUPTA, R. Adaptive digital baseband predistortion for RF power amplifier linearization. High Frequency Electronics, 2006, p.16-25.
- HRISTOV, V. Using assembler and C languages in the education of microcontrollers. In Proc. of the Conf. SAER’06. 2006, p. 200- 205.
- PANAGIEV, O. Analysis and Reduction on Nonlinear Distortions for Signals in the Broadband Cable Communication Systems. Dissertation, Technical University of Sofia (Bulgaria), 2006.
- JERUCHIM, M. C. Simulation of Communications System: Modeling, Methodology, and Techniques. 2nd ed., Kluwer Academic/Plenum Publishers, New York, 2000.

Keywords: Nonlinear distortions, Predistorter, Laser diode, CSO, CTB, Volterra kernels.

**J. Dobes**
[references] [full-text]

Using Volterra Series for an Estimation of Fundamental Intermodulation Products

The most precise procedure for determining the intermodulation products is to find a steady-state period of the signal first, and then to calculate its spectrum by means of the fast Fourier transform. However, this method needs time-consuming numerical integration over many periods of the faster signal even for enhanced methods for finding the steady state. In the paper, an efficient method for fast estimation of the fundamental intermodulation products is presented. The method uses Volterra series in a simple multistep algorithm which is compatible with a typical structure of the frequency-domain part of circuit simulators. The method is demonstrated by an illustrative testing circuit first, which clearly shows possible incorrect interpretation of the Volterra series. Thereafter, practical usage of the algorithm is demonstrated by fast estimation of the main intermodulation products of a low-voltage low-power RF CMOS fourquadrant multiplier.

- DOBES, J. Reliable CAD analyses of CMOS radio frequency and microwave circuits using smoothed gate capacitance models. AEU— International Journal of Electronics and Communications, 2003, vol. 57, no. 6, p. 372–380.
- SKELBOE, S. Computation of the periodic steady-state response of nonlinear networks by extrapolation methods. IEEE Transactions on Microwave Theory and Techniques, 1980, vol. 27, p. 161–175.
- VLACH, J., SINGHAL, K. Computer Methods for Circuit Analysis and Design. New York: Van Nostrand Reinhold Company, 1982.
- DOBES, J., BIOLEK, D., POSOLDA, P. An efficient steady-state analysis of microwave circuits. International Journal of Microwave and Optical Technology, 2006, vol. 1, no. 2, p. 284–289.
- DOBES, J. A steady-state add-on to the algorithm for implicit numerical integration. In Proceedings of the 51st Midwest Symposium on Circuits and Systems. Knoxville (Tennessee), 2008, p. 511–514.
- PETRENKO, A. I., VLASOV, A. I., TIMTSCHENKO, A. P. Tabular Methods of Computer-Aided Modeling. (In Russian.) Kiyv: Higher School, 1977.
- BRENAN, K. E., CAMPBELL, S. L., PETZOLD, L. R. Numerical Solution of Initial-Value Problems in Differential-Algebraic Equations. Philadelphia: SIAM, 1996.
- CHUA, L. O., LIN, P.-M. Computer-Aided Analysis of Electronic Circuits. Englewood Cliffs (New Jersey): Prentice-Hall, 1975.
- MASSOBRIO, G., ANTOGNETTI, P. Semiconductor Device Modeling With SPICE. 2nd ed. New York: McGraw-Hill, 1993.
- WAMBACQ, P., SANSEN, W. Distortion Analysis of Analog Integrated Circuits. Boston: Kluwer Academic Publishers, 1998.
- SHEU, B. J., SCHARFETTER, D. L., KO, P. K., JENG, M.-C. BSIM: Berkeley short-channel IGFET model for MOS transistors. IEEE Journal of Solid-State Circuits, 1987, vol. 22, no. 8, p. 558–566.
- CHENG, Y., HU, C. MOSFET Modeling & BSIM3 User’s Guide. Boston: Kluwer Academic Publishers, 1999.
- LIU,W. MOSFET Models for SPICE Simulation Including BSIM3v3 and BSIM4. New York: John Wiley & Sons, 2001.
- BUCHER, M., THEODOLOZ, F., KRUMMENACHER, F. The EKV MOSFET Model for Circuit Simulation. Lausanne: EPFL, 1998.
- SALAMA, M. K., SOLIMAN, A. M. Low-voltage low-power CMOS RF four-quadrant multiplier. AEU —International Journal of Electronics and Communications, 2003, vol. 57, no. 1, p. 74–78.
- PARKER, A. E., SKELLERN, D. J. A realistic large-signal MESFET model for SPICE. IEEE Transactions on Microwave Theory and Techniques, 1997, vol. 45, no. 9, p. 1563–1571.

Keywords: Steady-state algorithm, fast Fourier transform, numerical integration, Volterra series, CMOS, RF multiplier

**R. N. Baral, P. K. Singhal**
[references] [full-text]

Recent Techniques in Design and Implementation of Microwave Planar Filters

This paper details the techniques and initiatives made recently for improved response and simultaneous development of microwave planar filters. Although the objective of all the techniques is to design low cost filters with reduced dimensions, compact size with better frequency response, the methodological approaches are quite variant. The paper has gone through extensive analysis of all these techniques, their concept and design procedures.

- POZAR, D. M. Microwave Engineering. John Wiley, 2000.
- GUPTA, K. C., GARG, R., BAHL, I., BHARTIA, P. Microstrip Lines and Slotlines. London: Artech House, 1996.
- JIA-SHEN G. HONG, LANCASTER, M. J. Microstrip Filters for RF/Microwave Applications. John Wiley & Sons Inc., 2001.
- IE3D Software Release – 8, Developed by M/s Zeland Software Inc.
- Computer Simulation Technology, MICROWAVE STUDIO® (2006), AG.
- Applied Computational Science (ACS), Sonnet Software, Inc.
- HFSS, 3D Full Wave Electromagnetic Field Simulations, Ansoft Designer®.
- COHN, S. B. Parallel-coupled transmission-line-resonator filters. IRE Trans. Microw. Theory Tech., 1958, vol. MTT-6, no. 4, p. 223– 231.
- MATTAEI, G. L. Interdigital bandpass filters. IEEE Trans. Microw. Theory Tech., 1962, vol. MTT-10, no. 11, p. 479–491.
- CRISTAL, E. G. Tapped-line coupled transmission lines with applications to interdigital and combline filters. IEEE Trans. Microw. Theory Tech., 1975, vol. MTT-23, no. 12, p. 1007–1012.
- DENG, P.-H., LIN, Y.-S.,. WANG, C.-H, CHEN, C.-H. Compact microstrip bandpass filters with good selectivity and stopband rejection. IEEE Trans. Microw. Theory Tech., 2007, vol. 54, no. 2, p. 533–539.
- WU, C.-H., LIN, Y.-S.,. WANG, C.-H, CHEN, C.-H. Novel microstrip coupled line bandpass filters with shortened coupled sections for stopband extension. IEEE Trans. Microw. Theory Tech., 2007, vol. 54, no. 2, p. 540–546.
- MA, K.-X., MA, J.-G., YEO, K.-S., DO, M.-A. A compact size coupling controllable filter with separate electric and magnetic coupling paths. IEEE Trans. Microw. Theory Tech., 2006, vol. 54, no. 3, p. 1113–1119.
- MANDELBROT, B. B. Fractrals: Form, Chance and Dimension. Fhem M, Sanhciseo, USA, 1977.
- TCI, T., Z. Naturforch., 1988,
- PIETRONERO, L., TOSATTI, E., (eds.), Fractals in Physics. North- Holland, Amsterdam, The Netherlands, 1986.
- BEST, S. R. The fractal antenna: a comparison of fractal and non fractal geometries. In Antennas and Propagation Society International Symposium, IEEE vol. 3, 8-13 July 2001, p.146-149.
- ROMEU, J., RAHMAT- SAMII, Y. Fractal FSS: A Novel Dual- Band Frequency Selective Surface. IEEE Trans. on Ant. Propag. 2000, vol. 48, no. 7.
- JUNG-HYO, K., IL KWON, K., JONG- GWAN YOOK, HANKYU PARK, A slow-wave structure using Koch fractal slot loops. Microw. and Opt.Technology Letters, 2002, vol. 34, no.2, p. 87-88.
- LOPETEGI, T., LASO, M. A. G., FALCONE, F., MARTIN, F., BONACHE, J., GARCIA, J., PEREZ-CUEVAS, L., SOROLLA, M. GUGLIELMI, M. Microstrip “wiggly-line” and pass filters with multispurious ejection. IEEE Microwave and Wireless Component Letters, 2004, vol. 14, no. 11, p. 531-533.
- IL KWON KIM et. al. Fractal-shaped microstrip coupled-line bandpass filters for suppression of second harmonic. IEEE Trans. on Microw. Theory Techniques, 2005, vol. 53, no. 9, p. 2943-2948.
- KUO, J.-T., CHEN, S.-P., JIANG, M. Parallel-coupled microstrip filters with over-coupled end stages for suppression of spurious responses. IEEE Microw. Wireless Compon. Lett., 2003, vol. 13, no. 10, p. 440–442.
- PRIGIOBBO, A., BARRA, M., CASSINESE, A., CIRILLO, M., MARAFIOTI, F., RUSSO, R., VAGLIO, R. Superconducting resonators for telecommunication application based on fractal layout. Supercond. Sci. Technol., 2004, vol. 17, p. 427–431.
- JAGGARD, D. L. On Fractal Electrodynamics: Recent Advances in Electromagnetic Theory. Ed. Kriticos, H. N., Jaggard, D. L. New York: Springer-Verlag, 1990.
- 2001, Fractal and Space-Filling Transmission Lines, Resonators, Filters and Passive Network Elements. Patent WO 01/54221 A1.
- Fractus, The technology of nature®, S.A., Barcelona, Spain, 2001.
- WEN-LING CHEN, GUANG-MING WANG, YI-NA QI Fractal shaped hi-lo microstrip low pass filters with high pass band performance. Microw. and Opt. Technology Letters, 2007, vol. 49, no.10, p. 2577-2579.
- JOANNOPOULOS, J. D., et al. Photonic Crystals: Molding the Flow of Light. Princeton University Press, 1995.
- RADISIC, V., et al. Novel 2-D Photonic Band Gap structure for microstrip lines. IEEE Microw. Guided Wave Letter, 1998, vol. 8, no. 2, p. 69-71.
- RUMSEY, I.; PIKET-MAY, M.; KELLY, P. K. Photonic Bandgap structures used as filters in microstrip circuits. IEEE Microwave and Guided Wave Letters, 1998, vol. 8, no. 10, p. 336-338.
- SANTOSH BABU, G., SUBRAMANIAN, V., SIVASUBRAMANIAN, V., MURTHY, V. R. K. One-dimensional photonic band gaps at microwave frequencies for microwave filters. Ferroelectrics, 2005, vol. 327, p. 19-25.
- QIAN, Y., RADISIC, V., ITOH, T. Simulation and experiment of Photonic Band Gap structure for microstrip circuits. In APMC'97, 1997, p. 585-588.
- RUMSEY, I., PIKET-MAY, M., KELLY, P. K. Photonic Band Gap Structure used as filters in microstrip circuits. IEEE Microwave and Guided Wave Letters, vo1.8, no.10, 1998, p. 336-338.
- RADISIC, V., QIAN, Y., COCCIOLI, R., ITOH, T. Novel 2-D Photonic Band Gap structure for microwave line. IEEE Microwave and Guided Wave Letters, 1998, vol.8, no.2, p.69- 72.
- KIM, T., SEO, C. A Novel Photonic Bandgap structure for low-pass filter or wide stopband. IEEE Microwave and Guided Wave Letters, 2000, vol.10, no.1, p.13-15.
- YUN, T. Y., CHANG, K. One-dimensional Photonic Bandgap resonators and varactor tuned resonators. IEEE MTT-S. Int. Microwave Symp. Dig., 1999, p. 1629-1632.
- LENOIR, B., BAILLARGEAT, D., VERDEYME, S., GUILLON, P. Finite Element Method for rigorous design of microwave device using Photonic Bandgap structures. IEEE MTT-S Digest, 1998, p.1061- 1064.
- LOPETEGI, T., LASO, M. A. G., ERRO, M. J., FALCONE, F., SOROLLA, M. Bandpass filter in microstrip technology using Photonic Bandgap reflectors. In 29th European Microwave Conference. Munich (Germany), 1999, p. 337-340.
- LASO, M. A. G., LOPETEGI, T., ERRO, M. J., BENITO, D., GARDE, M. J., SOROLLA, M. Multiple-frequency-tuned Photonic Bandgap microstrip structures. IEEE Microwave and Guided Wave Letters, 2000, vol. 10, no.6, p. 220-222.
- XUE, Q., SHUM, K. M., CHAN, C. H. Novel 1-D microstrip PBG Cells., IEEE Microwave and Guided Wave Letters, 2000, vol. 10, no. 10, 2000, p. 403-405.
- NESIC, D., NESIC, A. Bandstop microstrip PBG filter with sinusoidal variation of the characteristic impedance and without etching in the ground plane. Microwave and Optical Technology Letters, 2001, vo1. 29, no. 6, p. 418-420.
- HANG, C. Y., RADISIC, V., QIAN, Y., ITOH, T. High efficiency power amplifier with novel PBG ground plane for harmonic tuning. In IEEE MTT-S International Microwave Symposium. Anaheim (CA), June 1999, p. 807-810.
- TSACHTSIRIS, G. F., SORAS, C. F., KARABOIKIS, M. P., MAKIOS, V. T. Analysis of a modified Sierpinski Gasket monopole antenna printed on dual band wireless devices. IEEE Transactions on Antennas and Propagation,2004, vol. 52, no. 10, p. 2571-2579.
- GONZALEZ, J. M., NAVARRO, M., PUNETE, C., ROMEU, J., AGUASCA, A. Active zone self-similarity of fractal-Sierpinski antenna verified using infra-red thermograms. ElectronicsLetters, 1999, vol. 35, no. 17, p.1393-1394.
- XIN LI, XIAO XING YIN, TIE JUN CUI, WEI HONG A new version of printed Sierpinski Multiband fractal antenna. In Antennas and Propagation Society International Symposium. 2004 IEEE vol. 4, 20-25 June 2004, p. 3457– 3460.
- JUN-SIK YUN, GEUN-YOUNG KIM, JUN-SEOK, PARK, DAL AHN, KWANG- YONG KANG, JAE-BONG LIM, A design of the novel coupled line bandpass filter using defected ground structure. 2000 IEEE MTT-S Digest, 2000, p. 327-330.
- Park, J. I., Kim, C. S., Kim, J., Park, J. S., Qian, Y., Ahn, D.,Itoh, T. Modeling of photonic bandgap and its application for the low-pass filter design. In 1999 Asia-Pacific Microwave Conf dig., Dec. 1999, vol. 2, p. 331-334.
- TIRADO-MENDEZ, J. A., JARDON-AGUILAR, H. Comparison of Defected Ground Structure (DGS) and Defected Microstrip Structure (DGS) behavior at High Frequencies. In Proceeding of 1st International Conference on Electrical and Electronics Engineering, 2004. Acapulco (Mexico), 8-10 September, 2004, p. 7-10.
- PAYMAN REZAEE, NASRIN NASR ESFAHANI, MAJID TAYARANI External Q computation by fuzzy inference method: Application to microstrip filter design. In Proceedings of ICMMT2008, p. 201-204.
- MIRAFTAB, V., MANSOUR, R. R. Computer-aided tuning of microwave filters using fuzzy logic. IEEE Trans. Microwave Theory Tech., 2002, vol. 50, p. 2781-2788.
- MIRAFTAB, V., MANSOUR, R. R. A Robust fuzzy-logic technique for computer-aided diagnosis of microwave filters. IEEE Trans. Microwave Theory Tech., 2004, vol. 52, p. 450-456.
- MIRAFTAB, V., MANSOUR, R. R. EM-based design tools for microwave circuits using fuzzy logic techniques. IEEE MTT-S, June 2003, vol. 1, p. 8-13.
- MIRAFTAB, V., MANSOUR, R. R. EM-based design tools for microwave circuits using fuzzy logic techniques. IEEE MTT-S, June 2003, vol. 1, p. 8-13.
- MIRAFTAB, V., MANSOUR, R. R. EM-based design tools for microwave circuits using fuzzy logic techniques. IEEE MTT-S, June 2003, vol. 1, p. 8-13.
- TAYARANI, M., KAMI, Y. Qualitative analysis in engineering electromagnetic: An application to general transmission lines. IEIEC Transactions on Electronics, 2001, vol. E84-C, no.3, p. 110-113.
- ISHIDA, H., ARAKI, K. Design and analysis of UWB bandpass filter with ring filter. In IEEE MTT-S Int. Microw. Symp. Dig., Jun. 2004, p. 1307–1310.
- ZHU, L., SUN, S., MENZEL, W. Ultra-wideband (UWB) bandpass filter using multiple-mode resonator. IEEE Microw. Wireless Compon. Lett., 2005, vol. 15, no. 11, p. 796–798.
- WANG, H., ZHU, L., MENZEL, W. Ultra-wideband (UWB) bandpass filter with hybrid microstrip/CPW structure. IEEE Microw. Wireless Compon. Lett., 2005, vol. 15, no. 12, p. 844–846.
- SUN, S., ZHU, L. Capacitive-ended interdigital coupled lines for UWB bandpass filters with improved out-ofband performances. IEEE Microw. Wireless Compon. Lett., 2006, vol. 16, no. 4, Aug. 2006, p. 440–442.
- HONG, J.-S., SHAMAN, H. An optimum ultra-wideband microstrip filter. Microw. Opt. Technol. Lett., Nov. 2005, vol. 47, no. 3, p. 230– 233.
- WONG, W. T., LIN, Y. S., WANG, C. H., CHEN, C. H. Highly selective microstrip bandpass filters for ultra-wideband applications. In Proc. Asia–Pacific Microw. Conf., Nov. 2005, p. 2850–2853.
- ZHANG-CHENG HAO, JIA-SHENG HONG, Ultra-wideband bandpass filter using multilayer liquid-crystal-polymer technology. IEEE Transactions on Microwave Theory and Techniques, 2008, vol. 56, no. 9, p. 2095-2100.
- VESELAGO, V. G. The electrodynamics of substrate with simultaneously negative values of ε and μ. Sov. Phys. Usp., 1968, vol. 10, no. 4, p. 509-514.
- PENDRY, J. B., HOLDEN, A. J., STEWART, W. J., YOUNGS, I. Extremely low frequency plasmons in metallic mesostructures. Phys.Rev. Lett., 1996, vol, 76, p. 4773.
- SMITH, D. R., VIER, D. C., PADILLA, W., NASSER, S. C. N., SCHULTZ, S. Loop-wire for investigating plasmons at microwave frequencies. Phys. Lett., 1999, vol. 75, no. 10, p. 1425-1427.
- SMITH, D. R., PADILLA, W., VIER, D. C., , NASSER, S. C. N., SCHULTZ, Composite medium with simultaneously negative permeability and permittivity. Phys. Rev. Lett., 2000, vol. 84, no. 18, p. 4184-4187.
- SHELBY, R. A., SMITH, D. R., SCHULTZ, S. Experimental verification of a negative index of refraction. Science, 2001, vol. 292, p.77-79.
- SANADA, A., CALOZ, C., ITOH, T. Characteristics of the composite right/left-handed transmission line. IEEE Microwave Wireless Compon. Lett., 2004, vol. 14, no. 2, p. 68-70.
- GRBIC, A., ELEFTHERIADES, G. V. Overcoming the diffraction limit with a planar left-handed transmission-line lens. Phys. Rev. Lett., 2004, vol. 92, p. 117403.
- LIM, S., CALOZ, C., ITOH, T. A reflecto-directive system using a composite right/left-handed (CRLH) leaky-wave antenna and heterodyne mixing. IEEE Microwave Wireless Compon. Lett., 2004, vol. 14, no. 4, p. 183-185.
- CALOZ, C., SANADA, A., ITOH, T.C. A novel composite right/lefthanded coupled-line directional coupler with arbitrary coupling level and broad bandwidth. IEEE Trans. Microwave Theory Tech., 2004, vol. 52, no. 3, p. 980-992.
- HORII, Y., CALOZ, C., ITOH, T. Super-compact multilayered lefthanded transmission line and diplexer application. IEEE Trans. Microwave Theory Tech., 2005, vol. 53, no. 4, p. 1527-1534.
- LIN, I., DEVINCENTIS, M., CALOZ, C., ITOH, T. Arbitrary dualband components using composite right/left-handed transmission lines. IEEE Trans. Microwave Theory Tech., 2004, vol. 52, no. 4, p. 1142- 1149.
- LAI, A., CALOZ, C., ITOH, T. Composite right/left-handed transmission line metamaterials. IEEE Microwave Magazine, 2004, vol. 9, p. 34-50.
- CALOZ, C., ITOH, T. A novel mixed conventional microstrip and composite right/left-handedbackward-wave directional coupler with broadband and tight coupling characteristics. IEEE Microwave Wireless Compon. Lett., 2004, vol. 14, no. 1, p. 31-33.
- ENGHETA, N. An idea for thin subwavelength cavity resonators using metamaterials with negative permittivity and permeability. IEEE Ant. Wireless Propagat. Lett., 2002, vol. 1, no. 1, p. 10-13.
- DECOOPMAN, T., VANBESIEN, O., LIPPENS, D. Demonstration of a backward wave in a single split ring resonator and wire loaded tinline. IEEE Microwave Wireless Compon. Lett., 2004, vol. 14, no. 11, p. 507-509.
- GRBIC, A., ELEFTHERIADES, G. V. Periodic analysis of a 2-D negative refractive index transmission line structure. IEEE Trans. on Antennas and Propag., 2003, vol. 51, no. 10, 2003, p. 2604-2611.
- ZIOLKOWSKI, R. W., ENGHETA, N. Metamaterial special issue introduction. IEEE Trans. Ant. Propag., 2003, vol. 51, no. 10, p. 2546-2549.
- CUMMER, S. A. Simulated causal sub wavelength focusing by a negative refractive index slab. Appl. Phys. Lett., 2003, vol. 82, p. 1503.

Keywords: Microstrip, Fractal, PBG (Photonic Band Gap), Defected Microstrip Structure (DMS), Defected Ground Structure (DGS).

**P. Protiva, J. Mrkvica, J. Machac**
[references] [full-text]

Universal Generator of Ultra-Wideband Pulses

An Ultra-Wideband (UWB) subnanosecond pulse generator is described in this paper. High amplitude Gaussian pulses are generated by a Step Recovery Diode (SRD) included in a novel pulse forming circuit. The pro-posed circuit solution utilizes the performance of the SRD effectively, without excessive requirements regarding the driver section of the generator. Monocycle pulses are then generated by an additional pulse forming network. A sim-ple transistor driver is also described, which transforms a TTL trigger signal to a driving pulse with the timing and amplitude parameters required by the SRD. Measurement results are presented, which show the proposed generator operating with stable output pulse parameters at arbitrary pulse repetition frequency up to 20 MHz. The generated monocycle pulses are 25 V in amplitude and approximately 500 ps in width.

- MILLER, E. K. Time-Domain Measurements in Electromagnetics. Springer, 1986.
- REED, J. H. An Introduction to Ultra Wideband Communication Systems. Prentice Hall PTR, 2005.
- OUSLIMANI, A., VERNET, G., HARDALLAH, H., ADDE, R. Large amplitude picosecond step generation with FETs. Electronics Letters, 1990, vol. 26, no. 19, p. 1563 - 1564.
- GERDING, M., MUSCH, T., SCHIEK, B. Generation of short electrical pulses based on bipolar transistors. Advances in Radio Science, 2004, no. 2, p. 7-12.
- Hewlett-Packard Application Note AN918: Pulse and Waveform Generation with Step Recovery Diodes. Hewlett-Packard, 1984.
- SMITH, P. W. Transient Electronics: Pulsed Circuit Technology. Wiley, 2002.
- HAN, J., NGUYEN, C. A new ultra-wideband, ultra-short monocycle pulse generator with reduced ringing. IEEE Microwave and Wireless Components Letters, 2002, vol. 12, no. 6, p. 206 - 208.
- TIELERT, R. Subnanosecond-pulse generator employing 2-stage pulse step sharpener. Electronics Letters, 1976, vol. 12, no. 3, p. 84 - 85.
- EVANS, S., READER, H. C. An impulse generator for antenna measurements in the time domain. Journal of Physics E: Scientific Instruments, 1988, vol. 21, p. 657 - 660.
- ZHANG, J., RAISANEN, A. A new model of step recovery diode for CAD. In Proc. IEEE MTT-S International Microwave Symposium Digest. Orlando (USA), 1995, vol. 3, p. 1459 - 1462.
- ASRD 800 Series Surface Mount Step Recovery Diode. Advanced Semiconductor, Inc., 1999.

Keywords: Ultra-Wideband, pulse generators, short pulses, step recovery diode, pulse shaping.

**J. Haze, L. Fujcik, R. Vrba, M. Pavlik, L. Michaeli**
[references] [full-text]

The Utilization of Novel Bandpass Sigma-delta Modulator for Capacitance Pressure Sensor Signal Processing

The paper deals with a novel approach to processing of pressure sensor signals. A bandpass sigma-delta modulator is used for this purpose. This technique is relatively new and it is not used widely, because this kind of modulator is usually utilized for wireless and video applications. Since the bandpass sigma-delta modulator works within its defined band it is resistant to offsets of its sub-circuits. The main stages of this modulator are implemented by means of switched-capacitor (SC) technique. The article presents the basic ideas of this approach and simulation results of the first order of ideal and real modulator. The paper also shows the design of the phase locked loop (PLL) block for synchronization of sensor signal and modulator driving signal. The simple evaluation board was fabricated for confirmation of the proposed principle. Also shown are the results of the chip testing, the modulator layout and the design and test results of the second order of bandpass sigma-delta modulator briefly.

- Ong, A. K., Wooley, B. A. A two-path bandpass SD modulator for digital IF extraction at 20 MHz. IEEE Journal of Solid-State Circuits, 1997, vol. 32, no. 12.
- Lao, CH., Leong, H., Au, K., Mok, K. U, S., Martins, R. P. A 10.7-MHz bandpass sigma-delta modulator using double-delay single-opamp SC resonator with double-sampling. In Proceedings of the 2003 International Sympsium on Circuits and Systems, 2003.
- Tabatabaei, A., Wooley, B. A. A two-path bandpass sigma–delta modulator with extended noise shaping. IEEE Journal of Solid-State Circuits, 2000, vol. 35, no. 12.
- Rodriguez-Vazquez, A., Medeiro, F., Janssens, E. CMOS Telecom Data Converters. Springer Verlag, 2004, 375 pages, ISBN 1402075464.
- Shu, K., Sanchez-Sinencio, E. CMOS PLL Synthesizers – Analysis and Design. Springer, 2005, ISBN 0-387-23669-4 (6).
- Smith, T., Nys, O., Chevroulet, M., DeCoulon, Y., Degrauwe, M. A 15 b electromechanical sigmadelta converter for acceleration measurements. In Proceedings of IEEE International Solid-State Circuits Conference - ISSCC `94, San Francisco (CA, USA), Feb. 1994 p.160-1.
- Brigati, S., Francesconi, F., Malcovati, P., Maloberti, F. A fourth-order single-bit switched-capacitor sigma-delta modulator for distributed sensor applications. IEEE Transactions on Instrumentation and Measurement, April 2004, vol. 53, pp. 266-270,.
- Saukoski, M., Aaltonen, L., Salo, T., Halonen, K. Readout electronics with bandpass delta-sigma A/D converter for a bulk micromachined capacitive gyroscope. In Proceedings of the IEEE Instrumentation and Measurement Technology Conference, 2005. IMTC. 16-19 May 2005, vol. 2, pp. 769 – 774.
- Petkov, V. P., Boser, B. E. A fourth-order sigma delta interface for micromachined inertial sensors. IEEE Journal of Solid-State Circuits, 2005,vol. 40, no. 8, pp. 1602 – 1609.
- Kulah, H., Chae, J., Yazdi, N., Najafi, K. Noise analysis and characterization of a sigma-delta capacitive microaccelerometer. IEEE J. of Solid-State Circuits, 2006, vol. 41, no. 2, pp. 352 to 361.
- Schreirer, R., Temes, C. G. Understanding Delta-Sigma Converters. IEEE Press, 2005.
- Unbehauen, R., Cichocki, A. MOS switched-capacitor and continuous-time integrated circuits and systems. Springer-Verlag, 1989.
- Baker, R. J., Harry, W. L., Boyce, D. E. CMOS Circuit Design, Layout, and Simulation. IEEE Press Series on Microelectronic Systems, 1998.

Keywords: Bandpass sigma-delta modulation, pressure measurement, capacitance sensor.

**M. Bobula, K. Danek, A. Prokes**
[references] [full-text]

Implementation of Industrial Narrow Band Communication System into SDR Concept

The rapid expansion of the digital signal processing has penetrated recently into a sphere of high performance industrial narrow band communication systems which had been for long years dominated by the traditional analog circuit design. Although it brings new potential to even increase the efficiency of the radio channel usage it also forces new challenges and compromises radio designers have to face. In this article we describe the design of the IF sampling industrial narrowband radio receiver, optimize a digital receiver structure implemented in a single FPGA circuit and study the performance of such radio receiver architecture. As an evaluation criterion the communication efficiency in form of maximum usable receiver sensitivity, co-channel rejection, adjacent channel selectivity and radio blocking measurement have been selected.

- ETSI EN 300 113-1 V1.6.1, Electromagnetic compatibility and Radio spectrum Matters (ERM), Part 1: Technical characteristics and methods of measurement. European Standard. ETSI, 07–2007.
- DANEK, K. Efficient use of mobile radio channel II. Radioengineering, June 2000, vol. 9, no.2, p.1-4.
- DODLEY, J. P., ERVING, R. H., RICE, C.W. In-building software radio architecture, design and analysis. IEEE article, 2000.
- LAWTON, M. C. Sensitivity analysis of radio architectures employing sample and hold techniques. In Radio Rec. and Assoc. Syst. 1995, Conf. publication No. 415, pp. 52-56.
- HAGHIGHAT, A. A review on essential and technical challenges of software defined radio. IEEE article, 2002.
- DWIVEDI, S., AMRUTUR, B., BHAT, N. Optimizing resolution of signals in a low-IF receiver. IEEE article, 2007.
- DA DALT, N., HARTENECK, M., SANDER, CH., WIESBAUER, A. On the jitter requirements of the sampling clock for analog-to-digital converters. IEEE Trans. on Circ. and Sys., 2002, vol. 49, no. 9, pp. 1354-60.
- LOSADA, R. A., LYONS, R. Reducing CIC filter complexity. IEEE Signal Proc. Magazine, July 2006.
- XILINX application note, “Distributed Arithmetic FIR Filter” V 9.0. Xilinx, Inc., April 2005, [online] 10-11-2008. Available at: http://www.xilinx.com/ipcenter/catalog/logicore/docs/da_fir.pdf
- YU, F. FPGA implementation of a fully digital FM demodulator. IEEE article, ICCS 2004.
- SCHNYDER, F., HALLER, CH. Implementation of FM Demodulator Algorithms on a High Performance Digital Signal Processor. MSc. Diploma Thesis. Technological University Nanyang, 2002.
- BOBULA, M., DANEK, K., PROKES, A. Simplified frame and symbol synchronization for 4–CPFSK with h=0.25. Radioengineering, 2008, vol.17, no. 2, p. 108 – 114.
- MILLER, P., CESARI, R. Wireless communication: Signal conditioning for IF sampling. 24 pages., SLOD006A, [online] 08-11-2008. Available at: http://focus.ti.com/lit/ml/sloa085/sloa085.pdf.
- Altera Corp., 2. Cyclone II Architecture CII51002-3.1. [online] 09-11-2008. available at: http://www.altera.com/literature/lit-cyc2.jsp.
- KESTER, W. MT-001: Taking the Mystery out of the Infamous Formula, “SNR=6.02N+1,76dB” and Why You Should Care. [online] 08-11-2008. Available at:http://www.analog.com/en/analog-to-digital-converters/ad-converters/products/tutorials/CU_tutorials_ MT-001/resources/fca.html

Keywords: Radio receivers, radio telemetry, communication system performance, digital radio, software defined digital radio.

**J. Lettl, R. Dolecek**
[references] [full-text]

EMC Increasing of PWM Rectifier in Comparison with Classical Rectifier

Pulse width modulated rectifier is a very popular topic nowadays. The modern industrial production demands continuous and lossless conversion of electrical energy parameters. This need leads to wide spread of power semiconductor converters. The rapid development in power electronics and microprocessor technology enables to apply sophisticated control methods that eliminate negative side effects of the power converters on the supply network. The phase controlled thyristor rectifiers overload the supply network with higher harmonics and reactive power consumption. That is why the PWM rectifier is being examined. In comparison with the phase controlled rectifier it can be controlled to consume nearly sinusoidal current with power factor equal to unity. Another advantage is its capability of energy recuperation. The PWM rectifier can assert itself for its good behavior in many applications, for example as an input rectifier in indirect frequency converter, or in traction. Traction vehicles equipped with PWM rectifier do not consume reactive power, do not load the supply network with higher harmonics, and the recuperation is possible. The paper deals with the PWM rectifier functional model realization and examination. Electromagnetic compatibility of PWM rectifier and classical phase controlled rectifier is compared on the basis of the input current harmonic analysis.

- WU, R., DEWAN S. B., SLEMON, G. R. A PWM AC-to-DC converter with fixed switching frequency. IEEE Transactions on Industry Applications, 1990, vol. 26, no. 5, pp. 880-885.
- LETTL, J. Analysis of high-performance AC-DC PWM converter. In Proceedings of International Conference on Electric Drives and Power Electronics. Strbske Pleso (Slovakia), 1990, vol. 1, pp. 8-13.
- WU, R., DEWAN, S. B., SLEMON, G. R. Analysis of an AC-to-DC voltage source converter using PWM with phase and amplitude control. IEEE Transactions on Industry Applications, 1991, vol. 27, no. 2, pp. 355-364.
- KHAN, B. H., DORADLA, S. R., DUBEY, G. K. A three-phase AC-DC GTO thyristor converter employing equal pulse-width modulation (EPWM). IEEE Transactions on Industry Applications, 1991, vol. 27, no. 2, pp. 370-379.
- LETTL, J. Analysis of a three-phase AC-to-DC PWM current-source converter including input filtering capacitors. Acta Technica CSAV, 1993, vol. 38, no. 5, pp. 507-534.
- ZACEK, J., LETTL, J. PWM voltage stiff rectifiers. In Proceedings of International Conference on Electric Drives and Power Electronics. High Tatras (Slovakia), 1994, vol. 2, pp. 219-224.
- LETTL, J., KUNZEL, K, SEBORSKY, S., ZACEK, J. Control of PWM rectifiers. In Proceedings of International Conference on Electrical Drives and Power Electronics. High Tatras (Slovakia), 1996, vol. 1, pp. 121-126.
- KUNZEL, K., LETTL, J., ZACEK, J. Some problems of PWM rectifiers. In Proceedings of 2nd International Conference on Unconventional Electromechanical and Electrical Systems UEES'96. Szczecin (Poland), 1996, pp. 779-784.
- LETTL, J., CHEKHET, E. M. Comparison of PWM rectifiers’ compatibility. In Proceedings of VIth Int. Conference on Problems of Present-day Electrotechnics. Kyiv (Ukraine), 2000, pp. 55-58.
- LETTL, J. Duality of PWM rectifiers. In Proceedings of 10th Electronic Devices and Systems Conference. Brno (Czech Republic), 2003, pp. 466-470.
- CEROVSKY, Z., MINDL, P. Mechanical characteristics of automotive hybrid drives using electric power splitting generator. In Proceedings of the 4th International Power Electronic and Motion Control Conference IPEMC 2004. Xi’an (China), 2004, vol. 2, pp. 615-619.
- LETTL, J., FLIGL, S. Matrix converter control system. In Proceedings of Progress in Electromagnetics Research Symposium PIERS 2005. Hangzhou, 2005, pp. 395-398.
- MINDL, P. Temperature distribution in PFC capacitors. In Proceedings of the 7th International Scientific Conference Electric Power Engineering. Brno(Czech Republic), 2006, pp. 403-406.
- RATZ, E., LETTL, J., RATZ, R. Limiting boundaries of vector controlled drives with optimized rotor flux. In Proceedings of XIVth International Symposium on Electric Machinery ISEM 2005. Prague (Czech Republic), 2006, pp. 190-196.
- LETTL, J. Matrix converter induction motor drive. In Proceedings of the 12th International Power Electronics and Motion Control Conference EPE-PEMC 2006. Portoroz(Slovenia), 2006, pp. 787 to 792.
- LETTL, J., FLIGL, S. Electromagnetic compatibility of matrix converter system. Radioengineering, 2006, vol. 15, no. 4, pp. 58-64.
- DOLECEK, R., CERNY, O. Analysis of 25 kV, 50 Hz traction supply system at Czech Railways. In Proceedings of the 6th WSEAS International Conference on Power Systems. Lisbon (Portugal), 2006, pp. 1259-1266.
- DOLECEK, R., HLAVA, K. Transient effects at power-supply system of Czech Railways from EMC viewpoint. Radioengineering, 2007, vol. 16, no. 1, pp. 40-44.
- ZDENEK, J. Optimizing of system partition and software architecture of distributed control computer of power electronics facility. In Proceedings of Progress in Electromagnetics Research Symposium PIERS 2007. Prague (Czech Republic), 2007, pp. 88-92.
- BAUER, J., LETTL, J. EMC comparison of phase controlled rectifiers and PWM rectifiers. In ELEN 2008 Conference Proceedings. Prague (Czech Republic), 2008.
- CHUNKAG, V., KAMNAM, U. Nearly unity power-factor of the modular three-phase AC to DC converter with minimized DC bus capacitor. IEEJ Transactions on Industrial Applications, 2008, vol. 128-D, no. 8, pp. 979-988.

Keywords: PWM rectifier, thyristor rectifier, pulse width modulation, control algorithm, measured waveforms, harmonic analysis, power factor.

**J. Novak, J. Simanek, O. Cerny, R. Dolecek**
[references] [full-text]

EMC of Frequency Controlled Electric Drives

The paper deals with solution possibilities of EMC for voltage inverters, which uses PWM (Pulse Width Modulation). The paper offers solution of interference suppression which is raised by operation of frequency controlled drives. Possible interferences caused by inverters and their solutions are described at the first part of paper and real solution examples at the end of paper.

- PAUL, C. R. Introduction to Electromagnetic Compatibility. Hoboken: John Wiley & Sons, Inc., 2006.
- LETTL, J., FLIGL, S. Electromagnetic compatibility of matrix converter system. Radioengineering, 2006, vol. 15, no. 4, p. 58 – 64.
- DOLECEK, R., HLAVA, K. Transient effects at power-supply system of the Czech Railways from EMC viewpoint. Radioengineering, 2007, vol. 16, no. 1, p. 40 – 44.
- WILDI, T. Electrical Machines, Drives, and Power Systems. 6th ed. Pearson Prentice Hall, 2006.

Keywords: EMC, inverter, converter, sinus filter.

**J. Holis, P. Pechac**
[references] [full-text]

Coexistence of Terrestrial and HAP 3G Networks during Disaster Scenarios

The aim of this paper is to show the possible coexistence of an HAP and a terrestrial component of 3G networks at a single carrier frequency. The main goal is to compare the basic parameters of terrestrial and HAP com-ponent 3G networks modeled in suburban (macrocell) and urban (macro/microcell) areas and to demonstrate the way they impact on each other. This study should present what we assume are the better capabilities of HAP 3G networks compared to their terrestrial counterparts. The parameters of the HAP and terrestrial component of 3G networks, were the terrestrial cells to be disabled during disasters, are also presented.

- DJUKNIC, G. M., FREIDENFELDS, J., OKUNEV, Y., Establishing wireless communications services via high-altitude aeronautical platforms: A concept whose time has come? IEEE Commun. Mag., Sep. 1997, pp. 128-35.
- TOZER, T. C., GRACE, D. High-altitude platforms for wireless communications. IEE Electron. Commun. Eng. J., June 2001, vol. 13, no. 3, pp.127-137.
- A Methodology for Co-channel Interference Evaluation to Determine Separation Distance from a System Using High-Altitude Platform Stations to a Cellular System to Provide IMT-2000 Service within the Boundary of an Administration. Int. Telecommunications Union, Recommendation ITU-R M.1641, 2003.
- COST 231 Final Report, Digital Mobile Radio: COST 231 VIEW on the Evolution Towards 3rd Generation Systems, Commission of the European Communities and COST Telecommunications, Brussels, 1999.
- Propagation Data and Prediction Methods Required for Design of Terrestrial Broadband Millimetric Radio Access System Operating in a Frequency Range About 20-50 GHz. Int. Telecommunications Union, Recommendation ITU-R P.1410, 2003.
- LEDL, P., PECHAC, P., “Area coverage simulations for millimeter point-to-multipoint systems using statistical model of buildings blockage. Radioengineering, 2002, vol.11, no. 4, pp. 43-47.
- SAUNDERS, S. R., ARGO-ZAVALA, A. Antennas and Propagation for Wireless Communication Systems. 2nd ed., John Wiley&Sons, 2007.
- ETSI, Selection Procedures for the Choice of Radio Transmission Technologies of the UMTS, (UMTS 30.30 version 3.1.0). Nov 1997.
- BERG, J-E. A Recursive method for street microcell path loss calculation. In IEEE International Symposium on Personal, Indoor and Mobile Radio Communications PIMRC’95, 1995, vol. 1, pp. 140-143.
- PARKS, M.A.N, EVANS, B. G., BUTT, G. High elevation angle propagation results applied to a statistical model and an enhanced empirical model. IEE Electronics Letters, September 1993, vol.29, no.19, pp. 1723-5.
- HOLIS, J., PECHAC, P. Elevation dependent shadowing model for mobile communications via High Altitude Platforms in built-up areas. IEEE Transactions on Antennas and Propagation, April 2008, vol. 56, no. 4, pp. 1078 – 1084.
- AXIOTIS, D. I., THEOLOGOU, M. E. An empirical model for predicting building penetration loss at 2 GHz for high elevation angles. IEEE Antennas and Wireless Propagation Letters, 2003, vol. 2, pp. 234-237.
- HOLIS, J., PECHAC, P. Penetration loss measurement and modeling for HAP mobile systems in urban environment. EURASIP Journal in Wireless Communications and Networking, April 2008.
- Minimum Performance Characteristics and Operational Conditions for High Altitude Platform Stations Providing IMT-2000 in the Bands 1885-1980 MHz, 2010-2025 MHz and 2110-2170 MHz and in Regions 1 and 3 and 1885-1980 MHz and 2110-2160 MHz in Region 2. Int. Telecommunications Union, Recommendation ITU-R M.1456, 2000.
- HOLIS, J., PECHAC, P. Provision of 3G mobile services in sparsely populated areas using High Altitude Platforms. Radioengineering, April 2008, vol. 17, no. 1, pp. 43-49.
- LAIHO, J., WACKER, A. NOVOSAD, T. Radio Network Planning and Optimization for UMTS. 2nd ed., John Wiley & Sons, 2005.
- SIAMITROS, K., DIMITRIOU, N., TAFAYOLLI, R. UMTS coverage planning using a High Altitude Platform Station (HAPS). In Proc. WPMC’02, Honolulu, 2002, pp. 1157-1159.
- HOLMA, H., TOSKALA, A. WCDMA for UMTS – HSPA Evolution and LTE. 4th ed., John Wiley & Sons, 2007.
- AXIOTIS, D. I., THEOLOGOU, M. E. 2 GΗz outdoor to indoor propagation at high elevation angles. In Proc. 13th International IEEE Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC), 2002, vol. 2, pp. 901–905.

Keywords: High altitude platforms (HAPs), UMTS, 3G, macro-, micro-cells.

**S. Costanzo, G. D. Massa**
[references] [full-text]

Wideband Phase Retrieval Technique from Amplitude-Only Near-Field Data

A wideband frequency behavior is demonstrated for a phaseless near-field technique of basically interferometric approach, which uses two identical probes interfering each other through a microstrip circuit and performing amplitude-only near-field measurements on a single scanning surface. The phase retrieval procedure is properly formulated to take into account the frequency dependence without changing neither the microstrip circuit nor the distance between the probes. Numerical simulations on a linear array of elementary sources are presented to validate the theoretical results.

- JOHNSON, R. C., ECKER, H. A., HOLLIS, J. S. Determination of far-field antenna patterns from near-field measurements. Proc. of IEEE, 1973, vol. 61, no. 12, p. 1668 - 1694.
- YAGHAJIAN, A. D. An overview of near-field antenna measurements. IEEE Trans. Antennas Propag., 1986, vol. 34, no. 1, p. 30 - 45.
- COSTANZO, S., DI MASSA, G. Direct far-field computation from bi-polar near-field samples. Journal of Electr. Waves and Appl., 2006, vol. 20, no. 9, p. 1137 - 1148.
- COSTANZO, S., DI MASSA, G. Efficient near-field to far-field transformation from plane-polar samples. Microwave Opt. Tech. Letters., 2006, vol. 48, no. 12, p. 2433 - 2436.
- COSTANZO, S., DI MASSA, G. Near-field to far-field transformation with planar spiral scanning. Progress in Electromagnetics Research, PIER, 2007, vol. 73, p. 49 - 59.
- BUCCI, O. M., D’ELIA, G., LEONE, G., PIERRI, R. Far-field pattern determination from near-field amplitude on two surfaces. IEEE Trans. Antennas Propag., 1990, vol. 38, no. 11, p. 1772 to 1779.
- BUCCI, O. M., D’ELIA, G., LEONE, G., PIERRI, R. Far-field computation from amplitude-only near-field data on two surfaces: cylindrical case. IEE Proc. H., 1992, vol. 139, no. 2, p. 143 - 148.
- ISERNIA, T., LEONE, G., PIERRI, R. New approach to antenna testing from near-field phaseless data: the cylindrical scanning. IEE Proc. H., 1992, vol. 139, no. 4, p. 363 - 368.
- FARHAD RAZAVI, S., RAHMAT-SAMII, Y. A new look at phaseless planar near-field measurements: limitations, simulations, measurements, and a hybrid solution. IEEE Antennas and Propagation Magazine, 2007, vol. 49, no. 2, p. 170 - 178.
- COSTANZO, S., DI MASSA, G., MIGLIORE, M. D. A novel hybrid approach for far-field characterization from near-field amplitudeonly measurements on arbitrary scanning surfaces. IEEE Trans. Antennas Propag., 2005, vol. 53, no. 6, p. 1866 - 1874.
- BUCCI, O. M., GENNARELLI, C., SAVARESE, C. Representation of electromagnetic fields over arbitrary surfaces by a finite and nonredundant number of samples. IEEE Trans. Antennas Propag., 1998, vol. 46, p. 351 - 359.

Keywords: Near-field methods, phase-retrieval, antenna measurements.

**D. Bonefacic, B. Rapinac, J. Bartolic**
[references] [full-text]

Slotted PIFA for Mobile Communication Devices

Slotted PIFA with capacitive loading for operation in the 880 / 960 MHz band is presented. The PIFA is intended for mobile terminals in GSM mobile communication network. The antenna is placed on a ground plane with dimensions of an average handheld device. It is optimized by using electromagnetic simulator and a prototype is manufactured. Calculated and measured results agree very well. Input impedance matching with SWR < 3 in the whole band was achieved. Maximum gain of 3.2 dBi is measured. Preliminary studies of the influence of the user\'s head and hand on the antenna characteristics have been performed.

- WHEELER, H. A. Fundamental limitations of small antennas. Proceedings of the IRE, 1947, vol. 35, pp. 1479-1484.
- CHU, L. J. Physical limitation on omni-directional antennas. Journal of Applied Physics, 1948, vol. 19, pp. 1163-1175.
- SKRIVERVIK, A. K., ZURCHER, J.-F., STAUB, O., MOSIG, J. R. PCS antenna design: The challenge of miniaturization. IEEE Antennas and Propag. Magazine, 2001, vol. 43, no. 4, pp. 12 to 26.
- MARTINEZ-VAZQUEZ, M. ACE small terminal antennas activities: a review of the state of the art. In Proc. of the 18th Int. Conference on Applied Electromagnetics and Communications (ICECom 2005). Dubrovnik (Croatia), 2005, pp. 29 to 32.
- WONG, K.L. Planar Antennas for Wireless Communications. Hoboken (New Jersey, USA): J. Wiley, 2003.
- HIRASAWA, K. Small antennas for mobile communications. In Proceedings Antenn00, Nordic Antenna Symposium. Lund (Sweden), 2000, pp. 11 - 15.
- KAN, H. K., WATERHOUSE, R. B. Small printed-wing antenna suitable for wireless handset terminals. Microwave and Optical Technology Letters, August 2001, vol. 30, no. 4, pp. 226 - 229,
- CHAIR, R., LUK, K. M., LEE, K. F., Miniature multilayer shorted patch antenna. Electronics Letters, 2000, vol. 36, no. 1, pp. 3 - 4.
- CHAIR, R., LUK, K. M., LEE, K. F. Miniature shorted dual-patch antenna. IEE Proc.-Microw. Antennas Propag., 2000, vol. 147, no. 4, pp. 273 - 276.
- KUO, J. S., WONG, K.-L. A low-cost microstrip-line-fed shorted-patch antenna for a PCS base station. Microwave and Optical Technology Letters, 2001, vol. 29, no. 3, pp. 146 - 148.
- VIRGA, K. L., RAHMAT-SAMII, Y. Low-profile enhanced-bandwidth PIFA antennas for wireless communications packaging. IEEE Transactions on Microwave Theory and Techniques, 1997, vol. 45, no. 10, pp. 1879 - 1888.
- HERSCOVICI, N., FUENTES OSORIO, M., PEIXEIRO, C. Minimization of a rectangular patch using genetic algorithms. In Proceedings of the 18th International Conference on Applied Electromagnetics and Communications (ICECom 2005). Dubrovnik (Croatia), 2005, pp. 37 - 40.
- KUMAR, G., RAY, K. P. Broadband Microstrip Antennas. Norwood (MA, USA): Artech House, 2003.
- JENSEN, M. A., RAHMAT-SAMII, Y. EM interaction of handsets antennas and a human in personal communications. Proceedings of the IEEE, 1995, vol. 83, no. 1, pp. 7-17.
- http://www.ansoft.com/products/hf/hfss/

Keywords: Small antenna, microstrip antenna, planar-inverted-F antenna, PIFA.

**P. Kovacs, Z. Raida, M. Martinez-Vazquez**
[references] [full-text]

Parametric Study of Mushroom-like and Planar Periodic Structures in Terms of Simultaneous AMC and EBG Properties

In the paper, the parametric analysis of a mushroom-like and a planar metallo-dielectric periodic structure with square unit cell and metallic patch is presented. First, the angular stability for different unit cell settings was studied. Second, restrictions for simultaneous behavior as artificial magnetic conductor (AMC) and electromagnetic band gap (EBG) are briefly discussed. Finally, main differences between the mushroom-like and the planar structure are specified and conclusions are formulated.

- SIEVENPIPER, D., ZHANG, L., BROAS, R. F. J, ALEXOPOLUS, N. G., YABLONOVITCH, E. High-impedance electromagnetic surfaces with a forbidden frequency band. IEEE Trans. on Microwave Theory and Techniques, 1999, vol. 47, no.11, p. 2059 – 2074.
- GOUSETTIS, G., FRESEDIS, A. P., VARDAXOGLOU, Y. C. Tailoring the AMC and EBG characteristics of periodic metallic arrays printed on grounded dielectric substrate. IEEE Transactions on Antennas and Propagation, January 2006, vol. 54, no.1, pp. 82-89.
- MONORCHIO, A., GENOVESI, S., SERRA, U., MANARA, G. Optimal design of artificial magnetic conductors including angular response. IEEE Antennas and Propagation Society International Symposium, 9-14 July, 2006, pp. 1931-1934.

Keywords: Artificial magnetic conductor, electromagnetic band gap, mushroom and planar structure, angular stability

**B. M. Vidal, Z. Raida**
[references] [full-text]

Synthesizing Sierpinski Antenna by Genetic Algorithm and Swarm Optimization

The paper discusses the synthesis of the Sierpinski antenna operating at three prescribed frequencies: 0.9 GHz, 1.8 GHz (both GSM) and 2.4 GHz (Bluetooth). In order to synthesize the antenna, a genetic algorithm and a particle swarm optimization were used. The numerical model of the antenna was developed in Zeland IE3D, optimization scripts were programmed in MATLAB. Results of both the optimization methods are compared and experimentally verified.

- MANDELBROT, B.B. The Fractal Geometry of Nature. New York: W.H. Freeman and Company, 1982.
- HAZDRA, P. Compact Fractal Antenna Structures. Technical Thesis. Prague: Czech Technical University, 2005.
- PUENTE, C., ROMEU, J., POUS, R., CARDAMA, A. On the behavior of the Sierpinski multiband antenna. IEEE Transactions on Antennas and Propagation, 1998, vol. 46, no. 4, p. 517–524.
- MONTOYA, A. Fractal Antennas (Antenas Fractales: un paso en la evolucion de las Telecomunicaciones). Mendellin-Colombia: Universidad de Antioquia. (In Spanish)
- SIAH, E. S., OOI, B. L., KOOI, P. S., XHOU, X. D. Experimental investigation of several novel fractal antennas-variants of the Sierpinski Gasket and introducing fractal FSS screens. In Proceedings of the 1999 Asia Pacific Microwave Conference, vol. 1, p. 170 – 173, 1999.
- ROBINSON, J., RAHMAT-SAMII, Y. Particle swarm optimization in electromagnetics. IEEE Transactions on Antennas and Propagation, 2004, vol. 52, no. 2, p. 397–407.
- GARCIA, J. M., ALBA E., LUQUE G. J. Algoritmos Basados en Cumulos de Particulas Para la Resolucion de Problemas Complejos. 2006. (In Spanish.)
- PEREZ LOPEZ, J. R. Contribucion a los metodos de optimizacion basados en procesos naturales y su aplicacion a las medidas de campo proximo. Santander: Universidad de Santander, 2005. (In Spanish.)
- TOWNSEND, A.A.R. Genetic Algorithm – A Tutorial [online]. Av.: www-course.cs.york.ac.uk/evo/SupportingDocs/TutorialGAs.pdf
- MICHAEL JOHNSON, J., RAHMAT-SAMII, Y. Genetic algorithms in engineering electromagnetics. IEEE Antennas and Propagation Magazine, 1997, vol. 39, no. 4. p. 7–21.
- LARRAÑAGA, P., INZA, I. Genetic Algorithms (Algoritmos Geneticos). Leioa: Universidad del Pais Vasco. (In Spanish.)
- IE3D User’s Manual. Fremont: Zeland Software, Inc., 2006.

Keywords: Fractal antenna, Sierpinski monopole, particle swarm optimization, genetic algorithm.

**P. V. Y. Jayasree, V. S. S. N. S. Baba, B. P. Rao**
[references] [full-text]

Shielding Effectiveness of Laminated Shields

Shielding prevents coupling of undesired radiated electromagnetic energy into equipment otherwise susceptible to it. In view of this, some studies on shielding effectiveness of laminated shields with conductors and conductive polymers using plane-wave theory are carried out in this paper. The plane wave shielding effectiveness of new combination of these materials is evaluated as a function of frequency and thickness of material. Conductivity of the polymers, measured in previous investigations by the cavity perturbation technique, is used to compute the overall reflection and transmission coefficients of single and multiple layers of the polymers. With recent advances in synthesizing stable highly conductive polymers these lightweight mechanically strong materials appear to be viable alternatives to metals for EM1 shielding.

- NAARMAN, H. Synthesis of new conductive electronic polymers. In Proc. Int. Cong. Synthetic Metals. Kyoto (Japan), June 1986.
- EHINGER, K., SUMMERFIELD, S., BAUHOFER, W., ROTH, S. DC and microwave conductivity of iodine-doped polyacetylene. J . Phys. C: Solid State Phys., 1984, vol. 17, pp. 3753-3762.
- NAISHADHAM, K., KADABA, P. K. Measurement of the microwave conductivity of a polymeric material with potential applications in absorbers and shielding. IEEE Trans. Microwave Theory Technol., July 1991, vol. 39, pp. 1158-1164.
- JARVA, W. Shielding tests for cables and small enclosures in the 1- to 10- GHz range. IEEE Trans. Electromagnetic Compatibility, February 1970, vol. 12, pp. 106-112.
- KONEFAL, T., DAWSON, J. F., MARVIN, A. C. Improved aperture model for shielding prediction. In IEEE International Symposium on Electromagnetic Compatibility, pp. 187-192, 2003.
- PRASAD KODALI, V. Engineering Electromagnetic Compatibility, Principles, Measurements and Technologies. S. Chand & company Ltd., 2000.
- PAUL, R. C. Introduction to Electromagnetic Compatibility. New York: John Wiley Interscience, 1992.
- SCHULZ, R. B., PLANTZ, V. C., BRUSH, D. R. Shielding theory and practice. IEEE Trans. Electromagn. Compat., Aug. 1988, vol. 30, pp. 187-201.

Keywords: Laminated shield, shielding effectiveness, frequency, conductive polymer.

**R. N. Baral, P. K. Singhal**
[references] [full-text]

Design of Microstrip Band Pass Fractal Filter for Suppression of Spurious Band

In this paper, the design and subsequent fabrication of a hairpin-line band pass filter has been proposed. This filter exhibits periodic frequency response. By proper design, the spurious bands are being suppressed significantly through the implementation of Koch fractal on the microstrip coupled line.

- Hong Jia-Shen, G., Lancaster, M. J. Microstrip Filters for RF/ Microwave Applications. John Wiley & Sons Inc., 2001.
- Pozar, D. M. Microwave Engg. John Wiley, 2000.
- Hsieh, Y., Wang, S.-M., Chang, C.-Y. Bandpass filters with resistive attenuators being located at 2nd and 4th spurious. In Proc. 34 rd EuMC, 2004, vol. 2, p. 729 – 732.
- Mandelbrot, B. B. The Fractal Geometry of Nature. New York: W. H. Freeman, 1983.
- Jaggard, D. L. On Fractal Electrodynamics. Recent Advances in Electromagnetic Theory. Ed. H N Kriticos and D L Jaggard. New York: Springer-Verlag, 1990.
- Kwon Kim, Il., et. al. Fractal-shaped microstrip coupled-line bandpass filters for suppression of second harmonic. IEEE Transactions on Microwave Theory and Techniques, 2005, vol. 53, no. 9, p. 2943 – 2948.
- IE3D Software Release – 8, Developed by M/s Zeland Software Inc.
- Cohen, N., Hohfeld, R. G. Fractal loops and small loop approximation. Commun. Quart., Winter 1996, p. 77 – 78.
- Mathaei, G., Young, L., Jones, E. M. T. Microwave Filter Impedance Matching Networks and Coupling Structures. Norwood: Artech House, 1980.

Keywords: Hairpin-line, Koch fractal, band pass filter, spurious band.

**H. Chaker, S. M. Meriah, F. T. Bendimerad**
[references] [full-text]

Optimization of Micro Strip Array Antennas Using Hybrid Particle Swarm Optimizer with Breeding and Subpopulation for Maximum Side-Lobe Reduction

In this paper, a technique based on hybrid particle swarm optimiser with breeding and subpopulation is presented for optimal design of reconfigurable dual-beam linear array antennas and planar arrays. In the amplitudephase synthesis, the design of a reconfigurable dual-pattern antenna array is based on finding a common amplitude distribution that can generate either a pencil or sector beam power pattern, when the phase distribution of the array is modified appropriately. The goal of this study is to introduce the hybrid model to the electromagnetic community and demonstrate its great potential in electromagnetic optimizations.

- ALPHONES, A., PASSOUPATHI, V. Null steering in phased arrays by positional perturbations: a genetic algorithm approach. Proc. IEEE Phased Arrays, 1996, pp. 203-207.
- GIES, D., RAHMAT-SAMII, Y. Particle swarm optimization for reconfigurable phase differentiated array design. Microwave and Optical Technol. Lett., August 2003, vol. 38, no. 3, pp. 168-175.
- ROBINSON, J., RAHMAT-SAMII, Y. Particle swarm optimization in Electromagnetic. IEEE Trans. Antennas & Propagation, Feb.2004, vol. 52, no. 2, pp. 397-407.
- ROBINSON, J., SINTON, S., RAHMAT-SAMII, Y. Particle swarm, genetic algorithm, and their hybrids: Optimization of a profiled corrugated horn antenna. IEEE AP-S, 2002, pp. 314-317.
- LOVBJERG, M., RASMUSSEN, T. K., KRINK, T. Hybrid particle swarm optimizer with breeding and subpopulations. In Proceedings of the Genetic and Evolutionary Computation Conference (GECCO). San Francisco (USA), July 2001.
- MERIAH, S. M., BENDIMERAD, F.T. Low level side lobes in thinned antennas arrays by switched supply law. Optimization by genetic algorithm. Annals of Telecommunications. 55, N°11-12, 2000, pp. 615-621.
- SPEARS, W. M. Simple subpopulation schemes. In Proceeding of the Evolutionary Programming Conference, 1994, pp. 296-307.
- KENNEDY, J., EBERHART, R. C. Particle swarm optimization. In Proceeding of the 1995 IEEE International Conference on Neural Networks, vol. 4, p. 1942-1948.
- SHI, Y., EBERHART, R. C. A modified particle swarm optimizer. IEEE International Conference on Evolutionary Computation. Anchorage (Alaska), May 4-9, 1998.
- SHI, Y., EBERHART, R. C. Parameter selection in particle swarm optimization. Evolutionary programming VII (1998), lecture notes in computer science 1447, 591-600. Springer
- KENNEDY, J. Small words and mega-minds: Effects of neighbourhood topology on particle swarm performance. In Proceedings of the 1999 Congress of Evolutionary Computation, vol. 3, p. 1931-1938. IEEE Press.
- MAHANTI, G. K., DAS, S., CHAKRABORTY, A. Design of phasedifferentiated reconfigurable array antennas with minimum dynamic range ratio. In IEEE Antennas and Wireless Propagation Letters, 2006, vol. 5, p. 262-264.

Keywords: Hybrid particle swarm, breeding and subpopulation, global optimization, phased array, reconfigurable array, planar array.

**K. B. Baltzis**
[references] [full-text]

An Efficient Finger Allocation Method for the Maximum Likelihood RAKE Receiver

In wideband wireless communication systems the RAKE receiver is commonly used to collect the resolvable multipath energy and counter the effects of fading through diversity. However, in channels with large delay and energy spread, its high complexity still remains a major issue. This motivates the study and application of computationally efficient finger placement algorithms that significantly reduce the receiver complexity with a reasonable performance loss. In this paper, a low–complexity maximum likelihood RAKE receiver, the Suboptimum – Maximum Power Minimum Correlation (S–MPMC) RAKE is proposed. The allocation of its first two fingers is based on the received signal correlation properties. Their positions determine also the placement of the rest of the fingers. Simulation results are provided to show the operation of the receiver and demonstrate its performance. Comparisons with relevant methods are performed to corroborate the merits of the proposal. The balance on the performance and the complexity of the technique makes it suitable for use in commercial wideband communication systems.

- WEBB, W. Wireless Communications: The Future. Chichester: John Wiley & Sons Ltd, 2007.
- JAVAID, U., RASHEED, T., MEDDOUR, D.-E., AHMED, T., PRASAD, N. R. A novel dimension of cooperation in 4G. IEEE Technology and Society Magazine, 2008, vol. 27, no. 1, p. 29-40.
- HOLIS, J., PECHAC, P. Simulation of UMTS capacity and quality of coverage in urban macro- and microcellular environment. Radioengineering, 2005, vol. 14, no. 4, p. 21-26.
- HOLMA, H., TOSKALA, A. (eds.). 4th ed. WCDMA for UMTS: HSPA Evolution and LTE. Chichester: John Wiley & Sons Ltd, 2007.
- LEE, J. S., MILLER, L. E., CDMA Systems Engineering Handbook. Boston: Artech House, 1998.
- KIM, K. J., KWON, S. Y., HONG, E. K., WHANG, C. Effect of tap spacing on the performance of direct-sequence spread spectrum RAKE receiver. IEEE Transactions on Communications, 2000, vol. 48, no. 6, p. 1029-1036.
- ALOUINI, M., SIMON, M. K. Performance analysis of coherent equal gain combining over Nakagami m-fading channels. IEEE Transactions on Vehicular Technology, 2001, vol. 50, no. 6, p. 1449 to 1463.
- LAU, W. C., ALOUINI, M., SIMON, M. K. Optimum spreading bandwidth for selective RAKE reception over Rayleigh fading channels. IEEE Journal on Selected Areas in Communications, 2001, vol. 19, no. 6, p. 1080-1089.
- GLISIC, S. G. Advanced Wireless Communications: 4G Cognitive and Cooperative Broadband Technology. 2nd ed. Chichester: John Wiley & Sons Ltd, 2007.
- PROAKIS, J. G., SALEHI, M., Digital Communications. 5th ed. New York: McGraw-Hill, 2007.
- DONG, X., BEAULIEU, N. C. Optimal maximal ratio-combining with correlated diversity. IEEE Communication Letters, 2002, vol. 6, no. 1, p. 22-24.
- BOTTOMLEY, G. E., OTTOSON, T., WANG, P.-E. A generalized RAKE receiver for interference suppression. IEEE Journal on Selected Areas in Communications, 2000, vol. 18, no. 8, p. 1536 to 1545.
- SUI, H., MASRY, E., RAO, B. D. Chip-level DS-CDMA downlink interference suppression with optimized finger placement. IEEE Transactions on Signal Processing, 2006, vol. 54, no. 10, p. 3908 to 3921.
- BALTZIS, K. B., SAHALOS, J. N. A novel RAKE receiver design for wideband communications. Wireless Personal Communications, 2007, vol. 43, no. 4, p. 1603-1624.
- KIM, B. S., BAE, J., SONG, I., KIM, S. Y., KWON, H. A comparative analysis of optimum and suboptimum rake receivers in impulsive UWB environment. IEEE Transactions on Vehicular Technology, 2006, vol. 55, no. 6, p. 1797-1804.
- CASSIOLI, D., WIN, M. Z., VATALARO, F., MOLISCH, A. F. Low complexity rake receivers in ultra-wideband channels. IEEE Transactions on Wireless Communications, 2007, vol. 6, no. 4, p. 1265-1275.
- HE, J., SALEHI, M. A new finger placement algorithm for the generalized RAKE receiver. In Proceedings of the 42nd Annual Conference on Information Sciences and Systems (CISS 2008). Princeton (USA), 2008, p. 335-340.
- WENG, J., XUE, G., LE-NGOC, T., TAHAR, S. Multistage interference cancellation with diversity reception for asynchronous QPSK DS/CDMA systems over multipath fading channels. IEEE Journal on Selected Areas in Communications, 1999, vol. 17, no. 12, p. 2162-2180.
- KIM, Y. W., KIM, Y. V., KIM, J. H., CHO, H.-S., SUNG, D. K. A comparison of system performance using two different chip pulses in multiple-chip-rate DS/CDMA systems. IEEE Transactions on Communications, 2001, vol. 49, no. 11, p. 1988-1996.
- JERUCHIM, M. C., BALABAN, P., SHANMUGAN, K. S. Simulation of Communications Systems: Modeling, Methodology and Techniques. 2nd ed. New York: Kluwer Academic/Plenum Publishers, 2000.
- EHRGOTT, M. Multicriteria Optimization. Berlin: Springer, 2005.
- COELLO, C. A. C., LAMONT, G. B., VAN VELDHUIZEN, D. A. 2nd ed. Evolutionary Algorithms for Solving Multi-Objective Problems. Berlin: Springer, 2007.
- CHAMBERS, L. D. (ed.). Practical Handbook of Genetic Algorithms: Complex Coding Systems, Volume III. New York: CRC Press LLC, 1999.
- GOLDSMITH, A. Wireless Communications. New York: Cambridge University Press, 2005.
- BOTTOMLEY, G. E., CAIRNS, D. A., COZZO, C., FULGHUM, T. L., KHAYRALLAH, A. S., LINDELL, P., SUNDELIN, M., WANG, Y.-P. Advanced receivers for WCDMA terminal platforms and base stations. Ericsson Review, 2006, vol. 8, no. 2, p. 54-58.

Keywords: Code division multiple access, correlation, maximum likelihood detection, multipath channels, rake diversity, wireless communication

**Z. Nemec, P. Bezousek**
[references] [full-text]

The Time Difference of Arrival Estimation of Wi-Fi Signals

The papers deals with a modeling of a Time- Difference of Arrival system for a subscriber station localization, based on the 802.11 standard wireless network. In the case of severe multipath effects the standard TDOA estimation methods, based on correlation of signals, received by conveniently displaced receiving stations show large errors. Thus, a new algorithm is proposed using received signals decomposition to a set of delayed replicas. This represents a linear estimation of reflected signals amplitudes. The described method leads to a better estimation of time differences of the signals, propagating on the direct paths between the emitter and the receiving stations.

- WOLFLE, G., HOPPE, R., ZIMMEMANN, D., LANDSTORFER, F. Enhanced localization technique within urban and indoor enviroments based on accurate and fast propagation models. European Wireless 2002, Firence (Italy), 2002.
- VELAYOS, H., KARLSSON, G. Limitations of range estimation in wireless LAN. In Proceedings of the 1st Workshop on Positioning, Navigation and Communication. Germany, 2004.
- BEZOUSEK, P. Position and velocity measurement accuracy analysis of the FMCW multilateration sensor. Scientific Papers of the University of Pardubice, Series B – The Jan Perner Transport Faculty 10, p. 5-17, Pardubice, 2004.
- NEMEC, Z. Application of a Data Communication to a Mobile Station Localization (in Czech). Dissertation, The Jan Perner Transport Faculty, University of Pardubice, 2007.

Keywords: Positioning, multipath propagation, correlated signals, wall reflections, signal parameters estimation, signal processing.

**M. Vondrasek, P. Sovka, T. Tichy**
[references] [full-text]

ACE Strategy with Virtual Channels

Cochlear implant is an electronic device, which can mediate hearing sensations to profoundly deaf people. Contemporary cochlear implants are sophisticated electronic devices; however, their performance could still be improved.

This paper describes an experiment we made in that direction: additional 21 virtual channels were implemented by sequential stimulation of adjacent intracochlear electrodes, and the ACE strategy with virtual channels (ACEv, Advanced Combination Encoder strategy with virtual channels) for the Nucleus® 24 Cochlear Implant System was created and verified in a clinical test with four patients.

- CLARK, G. Cochlear Implants, Fundamentals and Applications. New York: Springer NY, 2003. 830 p. ISBN 0-387-95583-6.
- ACE and CIS DSP Strategies. Software Requirements Specification, Cochlear Ltd. Australia, 2002.
- LAN, H., NIE, K. A Novel speech-processing strategy incorporating tonal information for cochlear implants. IEEE Transactions on Biomedical Engineering, 2004, vol. 51, no. 5, p. 752-760. ISSN 0018-9294.
- TONGOLA, G., BASSELI, M. Wavelet speech processing for cochlear implants. In EMBEC 2005, Prague (Czech Republic), 20-25 Nov. 2005.
- WILSON, B., ZERBI, M., LAWSON, D. Identification of virtual channel conditions on the basis of pitch. Third Quarterly Progress Report, NIH project NOI-DC-2-2401.
- POROY, O., LOIZOU, P. C. Pitch perception using virtual channels. In Conference on Implantable Auditory Prostheses, Asilomar, Monterey, CA, 2001.
- BUSBY, P. A., PLANT, K. Dual electrode stimulation using the Nucleus CI24RE cochlear implant: Electrode impedance and pitch ranking studies. Ear & Hearing, October 2005, vol. 26, no. 5, p. 504- 511.
- VONDRASEK, M., TICHY, T., SOVKA, P. Virtual channels in Nucleus® 24 Implant. [Invited unpublished lecture.] Cochlear Mechelen. 2006-10-13.
- HONET, C. Pitch Steering with Sequential Stimulation of Intracochlear Electrodes. Cochlear research report. Cochlear USA, 2006.
- DONALDSON, GS., KREFT, HA., LITVAK, L. Place-pitch discrimination of single- versus dual-electrode stimuli by cochlear implant users. Acoustic Soc Am 101:440-455, 2005.
- VONDRASEK, M., TICHY, T., SOVKA, P. Speech Reconstruction for Cochlear Implants. In EMBEC 2005, Prague(Czech Republic), 20-25 Nov. 2005.
- SVOBODOVA, K., TICHY, T., VACKAR, M., SEDLAK, S., TOPOL, M. Soubor percepce reci sluchem. Klinika otorhinolaryngologie a chirurgie hlavy a krku 1. LF UK, Fakulta elektrotechnicka CVUT, 1995. (in Czech)
- SWANSON, B. Nucleus® Reference manual. Cochlear Ltd. Australia, 2001.

Keywords: Cochlear Implant, Virtual Channels, Speech Processing.

**I. Baronak, P. Kvackaj**
[references] [full-text]

A New CAC Method Using Queuing Theory

The CAC (Connection Admission Control) method plays an important role in the ATM (Asynchronous Transfer Mode) network environment. The CAC is the first step in the prevention of congested states in the network topology, and conducts to the optimal network resources utilization.

The paper is aimed to propose an enhancement for a convolution method that is one of the statistical CAC methods used in ATM. The convolution method uses a buffer-less assumption in the estimation of the cell loss. Using formulas for the G/M/1 queuing system, the cell loss can be estimated as the buffer overflow probability.

In this paper, the proposed CAC method is compared with other three statistical CAC methods, and conclusions regarding the exploitation of the CAC method are presented.

- KAVACKY, M., BARONAK, I. Practical use of traffic control simulations for education purposes. In Proceedings of the 4th International Conference ICETA 2007. Stara Lesna (Slovakia), 2007.
- CHROMY, E., BARONAK, I. Contribution of call centre to regional development. In Proceedings of the 5th EURASIP Conference Focused on Speech and Image Processing, Multimedia Communications and Services. Smolenice (Slovakia), 2005, p. 212–215.
- GROSS, D., HARRIS, C. M. Fundamentals of Queuing Theory. 3rd ed. New York: J. Wiley and Sons, 1998.
- ENGEL, R. Design and Implementation of a New Connection Admission Control Algorithm Using a Multi-state Traffic Source Model. Diploma Thesis. St. Louis (USA): Department of Computer Science, Washington University, 1996. Available at: www.seas.wustl.edu/Research/FileDownload.asp?58.
- MARZO I LAZARO, J. L. Enhanced Convolution Approach for CAC in ATM Networks: An Analytical Study and Implementation. Girona (Italy): University of Girona, 1996. Available at: http://www.tdx.cesca.es/TDX-1003101-155128/
- KOUVATSOS, D., et al. Performance Evaluation and Applications of ATM Networks. Kluwer International Series in Engineering and Computer Science. Boston (USA): Kluwer Academic Publishers, 2002.
- ROSE, O. Traffic Modeling of Variable Bit Rate MPEG Video and its Impacts on ATM Networks. Ph.D. Dissertation. Wurzburg (Germany): Bayerische Julius-Maximilians-Universitat, 1997.
- Video Traces for Network Performance Evaluation. Available at: http://trace.eas.asu.edu/tracemain.html
- The ATM Forum: Traffic Management Specification Version 4.0, af-95-0013R13, Letter Ballot, April 1996.
- MATLAB and Simulink User’s Guide. Natick (USA): The Math- Works, Inc. Available at: http://www.mathworks.com/

Keywords: Connection Admission Control (CAC), Asynchronous Transfer Mode (ATM), convolution method.

**M. Dobrovolny, P. Bezousek, M. Hajek**
[references] [full-text]

Application of a Cumulative Method for Car Borders Specification in Image

The paper deals with low-level car detection methods in images. The car detection is an integral part of all intelligent car cruise systems. This article describes the method for suppression of the edges produced by classical edge\'s operators, based on application of the cumulative method. The designed method uses the non-stationary property of the picture background in time-realizations of the image signal.

- BETKE, M., HARITAGLU, E., DAVIS, L. Multiple vehicle detection and tracking in hard real time. In IEEE Intelligent Vehicles Symposium, pp. 351–356, 1996.
- ZHAO, T., NEVATIA, R. Car detection in low resolution aerial images. In IEEE Int. Conf. Computer Vision, p. 710-717, 2001.
- YING, R., CHIN-SENG, C., YEONG, K. Motion detection with nonstationary background. Machine Vision and Applications, Springer-Verlag, 2003
- DOBROVOLNY, M. On-road vehicle detection based on image processing. Doctoral dissertation, University of Pardubice, 2008
- CHRISTOPHE, P. B. Discrete wavelet analysis for fast optic flow computation. Applied and Computational Harmonic Analysis, July 2001, vol. 11, no. 1, pp. 32-63.
- BRUHN, A., WEICKERT, J., SCHNORR, C. Lucas/Kanade Meets Horn/Schunck: Combining local and global optic flow methods. International Journal of Computer Vision, 2005, vol. 61, no. 3, p. 211–231.
- CHATUVERDI, P. Real-time identification of driveable areas in semi-structured terrain. Proc. SPIE, vol. 4364, p. 302-312, Unmanned Ground Vehicle Technology III, 2001, 2001SPIE.4364..302C.
- ANDREONE, L., ANTONELLO, P. C., BERTOZZI, M., BROGGI, A., FASCIOLI, A., RANZATO, D. Vehicle detection and localization in infra-red images. In The IEEE 5th International Conference on Intelligent Transportation Systems, 3-6 September 2002, Singapore. pp. 141-146.
- CASTELMAN, K. Digital image processing. Prentice Hall, September 2, 1995, ISBN: 0-132114-674
- FORSYTH, D., PONCE, J. Computer Vision: A Modern Approach. Prentice Hall, August 24, 2002, ISBN: 0-130851-98-1.

Keywords: Image processing, cumulative method, Intelligent Driver Systems (IDS), car detection, edge detection.

**M. Adam, F. Rossant, F. Amiel, B. Mikovikova, T. Ea**
[references] [full-text]

Eyelid Localization for Iris Identification

This article presents a new eyelid localization algorithm based on a parabolic curve fitting. To deal with eyelashes, low contrast or false detection due to iris texture, we propose a two steps algorithm. First, possible edge candidates are selected by applying edge detection on a restricted area inside the iris. Then, a gradient maximization is applied along every parabola, on a larger area, to refine parameters and select the best one. Experiments have been conducted on a database of 151 iris that have been manually segmented. The performance evaluation is carried out by comparing the segmented images obtained by the proposed method with the manual segmentation. The results are satisfactory in more than 90% of the cases.

- MANSFIELD, T., KELLY, G., CHANDLER, D., KANE, J. Biometric Product Testing Report. CESG/BWG Biometric Test Programme. National Physical Laboratory, UK, 2001.
- DAUGMAN, J. How iris recognition works. IEEE Trans. CSVT, 2004, vol. 14, no. 1, pp. 21-30.
- MA, L., TAN, T., WANG, Y., ZHANG, D. Personal identification based on iris texture analysis. IEEE Trans. PAMI, 2003, vol. 25, no. 12, pp. 1519-1533.
- WILDES, R. P. Iris recognition: An emerging biometric technology. Proceedings of the IEEE, 1997, vol. 85, no. 9, pp. 1348 to 1363.
- CHEN, Y., DASS, S. C., JAIN, A. K. Localized iris image quality using 2-D wavelet. In Advances in Biometrics, International Conference, ICB 2006, Hong Kong (China), January 5-7, 2006. Proceedings. Lecture Notes in Computer Science 3832 Springer 2006, 373-381.
- CUI, J., WANG, Y., TAN, T., MA, L., SUN, Z. A fast and robust iris localization method based on texture segmentation. Biometric technology for human identification. In Proceedings of the SPIE, 2004, vol. 5404, pp. 401-408.
- SANDOWSKI, W., GRABOWSKI, K., NAPIERALSKA, M., ZUBERT. M. Eyelids localization method designed for iris recognition system. In 14th International Conference on Mixed Design of Integrated Circuits and Systems, 2007.
- RYDGREN, E., EA, T., AMIEL, F., ROSSANT, F. AMARA, A. Iris Features Extraction Using Wavelet Packets. In IEEE International Conference on Image Processing 2004, ICIP 2004. Singapore, 2004, vol. 2, pp. 1348-1363.
- ROSSANT, F., TORRES ESLAVA, M., EA, T., AMIEL, F., AMARA, A. Iris identification and robustness evaluation of a wavelet packets based algorithm. In IEEE International Conference on Image Processing 2005, ICIP 2005. Geneva (Switzerland), 2004, vol. 3, pp. 257-260.
- PERONA, M., MALIK, J. Scale-space and edge detection using anisotropic diffusion. IEEE Transaction on Pattern Analysis and Machine Intelligence, 1990, vol. 12, no. 7, pp. 629-639.
- CANNY, J. A computational approach to edge detection. IEEE Transaction on Pattern Analysis and Machine Intelligence, 1986, vol. 8, no. 6, pp. 679-698.
- MORIZET, N., AMIEL, F., DRIS-HAMED, I, EA, T. A comparative implementation of PCA face recognition algorithm. In IEEE International Conference on Electronics, Circuits and Systems. Marrakech (Morocco) , December 11-14, 2007.

Keywords: Biometric identification, iris analysis, eyelid segmentation, edge selection, curve fitting.

**F. Rossant, F. Amiel, T. Ea, C. M. Martinez, M. Paques**
[references] [full-text]

Enhancement of Optical Coherence Tomography Images of the Retina by Normalization and Fusion

This paper describes an image processing method applied to Optical Coherence Tomography (OCT) images of the retina. The aim is to achieve improved OCT images from the fusion of sequential OCT scans obtained at identical retinal locations. The method is based on the normalization of the acquired images and their fusion. As a result, a noise reduction and an image enhancement are reached. Thanks to the resulting improvement in retinal imaging, clinical specialists are able to evaluate more efficiently eyes pathologies and anomalies. This paper presents the proposed method and gives some evaluation results.

- StratusOCT tomography, Zeiss documentation, http://www.zeiss.com/C125679E0051C774/Contents- Frame/2BF7095D5578B41D882572430063F9AD.
- Carl Zeiss Meditec AG, Goeschwitzer Str 51-52, 07745 Jena, Germany, http://www.zeiss.com/.
- KENT, C. Taking OCT technology to the next level. Review of Ophthalmology, 2006, vol. 13:06, Issue 6/7/2006.
- SANDER, B., LARSEN, M., THRANE, L., HOUGAARD, J. L., JØRGENSEN, T. M. Enhanced optical coherence tomography imaging by multiple scan averaging. Br. J. Ophthalmol. 2005; vol. 89; p. 207-212 doi:10.1136/bjo.2004.045989, December 2005.
- GONZALES, R. C., WOODS, R. E. Digital Image Processing. New Jersey: Prentice Hall, 2002.
- SETHIAN, J. A. Level Set Method and Fast Matching Methods. Cambridge University Press, 1999.

Keywords: Optical coherence tomography, denoising, filtering, correlation, fusion

**B. Godara, A. Fabre**
[references] [full-text]

A New Application of Current Conveyors: The Design of Wideband Controllable Low-Noise Amplifiers

The aim of this paper is three-fold. First, it reviews the low-noise amplifier and its relevance in wireless communications receivers. Then it presents an exhaustive review of the existing topologies. Finally, it introduces a new class of LNAs, based on current conveyors, describing the founding principle and the performances of a new single-ended LNA. The new LNAs offer the following notable advantages: total absence of passive elements (and the smallest LNAs in their respective classes); wideband performance, with stable frequency responses from 0 to 3 GHz; easy gain control over wide ranges (0 to 20 dB). Comparisons with other topologies prove that the new class of LNA greatly advances the state of the art.

- GODARA, B., FABRE, A. A versatile wideband impedance matching circuit based on current conveyors. Institute of Engineering and Technology (IET); Electronics Letters, vol. 43, no. 6, March 2007.
- GODARA, B., FABRE, A. State of the art for differential circuits in wireless transceivers; A new wideband active balun in SiGe- BiCMOS technology. Turkish Journal of Electrical Engineering and Computer Sciences; Special Issue. 2006, vol.: 14, no. 3, pp. 355 to 386.
- GIRLANDO, G., PALMISANO, G. Noise figure and impedance matching in RF cascode amplifiers. IEEE Transactions on Circuits and Systems – II : Analog and Digital Signal Processing, 1999, vol. 46, no. 11, pp. 1388 – 1396.
- HAZENBOOM, S. et al. A comparison of substrate noise coupling in lightly and heavily doped CMOS processes for 2.4-GHz LNAs. IEEE JSSC, 2006, vol. 41, no. 3, pp. 574 – 587.
- JEON, Y-J. et al. Monolithic feedback low noise X-band amplifiers using 0.5-μm GaAs MESFET’s: Comparative theoretical study and experimental characterization. IEEE JSSC, 1998, vol. 33, no. 2, brief papers, pp. 275 – 279.
- MYOUNG, S-S. et al. Low-noise and high-linearity LNA based on InGaP/GaAs HBT For 5.3-GHz WLAN. Microwave and Optical Technology Letters, 2005, vol. 46, no. 6, pp. 550 – 553.
- RUDELL, J. C. et al. A 1.9-GHz wide-band IF double conversion CMOS receiver for cordless telephone applications. IEEE JSSC, 1997, vol. 32, no. 12, pp. 2071 – 2088.
- ZHANG, F. et al. Low-power programmable gain CMOS distributed LNA. IEEE JSSC, 2006, vol. 41, no. 6, pp. 1333 – 1343.
- ABIDI, A. A., et al. De-embedding the noise figure of differential amplifiers. IEEE JSSC, 1999, vol. 34, no. 6, pp. 882 – 885.
- VAN DER HEIJDEN, M. P. et al. On the design of unilateral dualloop feedback low-noise amplifiers with simultaneous noise, impedance, and IIP3 match. IEEE JSSC, 2004, vol. 39, no. 10, pp. 1727 – 1736.
- DUBOIS, M-A. et al. Monolithic above-IC resonator technology for integrated architectures in mobile and wireless communication. IEEE JSSC, 2006, vol. 41, no. 1, pp. 7 – 16.
- BEVILACQUA, A., NIKNEJAD, A. M. An ultrawideband CMOS low-noise amplifier for 3.1–10.6-GHz wireless receivers. IEEE Journal of Solid-State Circuits, 2004, vol. 39, no. 12, pp. 2259 to 2268.
- ISMAIL, A., et al. A 3–10-GHz low-noise amplifier with wideband LC-ladder matching network. IEEE JSSC, 2004, vol. 39, no. 12, pp. 2269 – 2277.
- KIM, C-W. et al. An ultra-wideband CMOS low noise amplifier for 3–5-GHz UWB system. IEEE JSSC, 2005, vol. 40, no. 2, pp. 544 to 547.
- KIM, N. et al. A cellular-band CDMA 0.25-μm CMOS LNA linearized using active post-distortion. IEEE JSSC, 2006, vol. 41, no. 7, pp. 1530 – 1534.
- SCHMIDT, A. et al. A universal dual band LNA implementation in SiGe technology for wireless applications. IEEE JSSC, 2001, vol. 36, no. 7, brief papers, pp. 1127 – 1131.
- BRUCCOLERI, F., KLUMPERINK, E. A. M., NAUTA, B. Wideband CMOS low-noise amplifier exploiting thermal noise canceling. IEEE Journal of Solid-State Circuits, 2004, vol. 39, no. 2, pp. 275 to 282.
- SHAEFFER, D. K. et al. A 1.5-V, 1.5-GHz CMOS low noise amplifier. IEEE JSSC, 1997, vol. 32, no. 5, pp. 745 – 759.
- SHANA’A, O. et al. Frequency-scalable SiGe Bipolar RF front-end design. IEEE JSSC, 2001, vol. 36, no. 6, pp. 888 – 895.
- HUANG, Q. et al. GSM transceiver front-end circuits in 0.25μm CMOS. IEEE JSSC, 1999, vol. 34, no. 3, pp. 292 – 303.
- ABOU-ALLAM, E., NISBET, J. J., MALIEPAARD, M. C. Lowvoltage 1.9-GHz front-end receiver in 0.5-μm CMOS technology. IEEE Journal of Solid-State Circuits, 2001, vol. 36, no. 10, pp. 1434 – 1443.
- GATTA, F., SACCHI, E., SVELTO, F., VILMERCATI, P., CASTELLO, R. A 2-dB noise figure 900-MHz differential CMOS LNA. IEEE Journal of Solid-State Circuits, 2001, vol. 36, no. 10, pp. 1444 – 1452.
- KARANICOLAS, N. A 2.7-V 900-MHz CMOS LNA and mixer. IEEE JSSC, 1996, vol. 31, no. 12, pp. 1939 – 1944.
- LEROUX, P. et al. A 0.8-dB NF ESD-protected 9-mW CMOS LNA operating at 1.23 GHz. IEEE JSSC, 2002, vol. 37, no. 6, brief papers, pp. 760 – 765.
- CHARLON, O. et al. A low-power high-performance SiGe BiCMOS 802.11a/b/g transceiver IC for cellular and Bluetooth co-existence applications. IEEE JSSC, 2006, vol. 41, no. 7, pp. 1503 – 1512.
- ROGIN, J. et al. A 1.5-V 45-mW direct-conversion WCDMA receiver IC in 0.13-_m CMOS. IEEE JSSC, 2003, vol. 38, no. 12, pp. 2239 – 2248.
- YAMAMOTO, K. et al. A 2.4-GHz-band 1.8-V operation singlechip Si-CMOS T/R-MMIC front-end with a low insertion loss switch. IEEE JSSC, 2001, vol. 36, no. 8, pp. 1186 – 1197.
- CASSAN, D. J., LONG, J. R. A 1-V transformer-feedback low-noise amplifier for 5-GHz wireless LAN in 0.18-μm CMOS. IEEE Journal of Solid-State Circuits, 2003, vol. 38, no. 3, pp. 427 – 435.
- REYNOLDS, S. K. et al. A direct-conversion receiver IC for WCDMA mobile systems. IEEE JSSC, 2003, vol. 38, no. 9, pp. 1555 to 1560.
- ROSSI, P. et al. A variable gain RF front-end, based on a voltage– voltage feedback LNA, for multistandard applications. IEEE JSSC, 2005, vol. 40, no. 3, pp. 690 – 697.
- ADISENO, ISMAIL, M., OLSSON, H. A wide-band RF front-end for multiband multistandard high-linearity low-IF wireless receivers. IEEE Journal of Solid-State Circuits, 2002, vol. 37, no. 9, pp. 1162 to 1168.
- SIVONEN, P. et al. A 1.2-V RF front-end with on-chip VCO for PCS 1900 direct conversion receiver in 0.13μm CMOS. IEEE JSSC, 2006, vol. 41, no. 2, pp. 384 – 394.
- RYYNANEN, J. et al. A single-chip multimode receiver for GSM900,DCS1800, PCS1900, and WCDMA. IEEE JSSC, 2003, vol. 38, no. 4, pp. 594 – 602.
- GRAMEGNA, G. et al. A sub-1-dB NF 2.3-kV ESD-protected 900- MHz CMOS LNA. IEEE JSSC, 2001, vol. 36, no. 7, pp. 1010 to 1017.
- CHEN, H.-K., CHEN, H.-J. A 5.2-GHz cascade-MOS 0.35-μm BiCMOS technology ultra-lowpower LNA using a novel floatingbody method. Wiley Periodicals, Inc. Microwave and Optical Technology Letters, 2005, vol. 45, no. 5, pp. 363 – 367.
- HE, Q. et al. Low-power, high-gain, and high-linearity SiGe BiCMOS wide-band low-noise amplifier. IEEE JSSC, 2004, vol. 39, no. 6, pp. 956 – 959.
- WELCH, B. et al. A 20-GHz low-noise amplifier with active balun in a 0.25-_m SiGe BICMOS technology. IEEE JSSC, 2005, vol. 40, no. 10, pp. 2092 – 2097.
- LISCIDINI, A. et al. A 0.13 _m CMOS front-end, for DCS1800/UMTS/802.11b-g with multiband positive feedback lownoise amplifier. IEEE JSSC, 2006, vol. 41, no. 4, pp. 981 – 989.
- FABRE, A., SAAID, O., WIEST, F., BOUCHERON, C. Highfrequency applications based on a new current controlled conveyor. IEEE Transactions on Circuits and Systems – I : Fundamental Theory and Applications, 1996, vol. 43, no. 2, pp. 82 – 91.
- SEGUIN, F. Etude et realisation de circuits convoyeurs de courant de seconde generation en technologie BiCMOS. Application à l’amplification RF reglable. PhD dissertation, Univ. Bordeaux 1, France, Dec. 2001 (in French).
- OUELLETTE, J. Silicon–Germanium gives semiconductors the edge. The Industrial Physicist magazine (American Institute of Physics), June-July 2002, pp. 22 – 25.
- BILLONNET, L. et al. Revue des RFICs pour LNA et Filtres; conception caracterisation modelisation de fonctions RF et Mircoondes Integrees faible bruit – filtrage actif. Atelier “projets et R&D en radioastronomie”, Nov. 2003,( in French).
- JOHN, J. P. et al. Optimization of a SiGe:C HBT in a BiCMOS technology for low power wireless applications. In Proceedings, BCTM Bipolar/BiCMOS Circuits and Technology Meeting, 2002, pp. 193- 196, Sept. 2002.
- JOSEPH, A. et al. Advances in SiGe HBT BiCMOS technology. In 2004 Topical Meeting on Silicon Monolithic Integrated Circuits in RF Systems, pp. 1- 4, Sept. 2004.
- MAUFROID, D. Silicon integration : SiGe wide band mixed-signal SoC : the Promura project. Software-Defined Radio Forum, Sept. 2000.
- The BICMOS6G Design Kit; Version 7.0; Opus 4.4.6.100.29_57
- Circuits Multi-Projets website : http://cmp.imag.fr.
- Karl Suss PA200, Modular probe system user manual, Karl Suss, Germany, 2001, ww.suss.com.

Keywords: All-transistor circuits, low-noise amplifiers, multiband receivers, wideband RF circuits.

**P. Drexler, P. Fiala**
[references] [full-text]

Utilization of Faraday Mirror in Fiber Optic Current Sensors

Fiber optic sensors dispose of some advantages in the field of electrical current and magnetic field measurement, like large bandwidth, linearity, light transmission possibilities. Unfortunately, they suffer from some parasitic phenomena. The crucial issue is the presence of induced and latent linear birefringence, which is imposed by the fiber manufacture imperfections as well as mechanical stress by fiber bending. In order to the linear birefringence compensation a promising method was chosen for pulsed current sensor design. The method employs orthogonal polarization conjugation by the back direction propagation of the light wave in the fiber. The Jones calculus analysis presents its propriety. An experimental fiber optic current sensor has been designed and realized. The advantage of the proposed method was proved considering to the sensitivity improvement.

- GAUGITSCH, M., HAUSER, H. Optimization of a magneto-optical light modulator. Journal of Lightwave Technology, 1999, vol. 17, no. 12, p. 2633 - 2644.
- CRAIG, A. E., CHANG, K. Handbook of Optical Components and Engineering. New Jersey: John Wiley & Sons, Inc., 2003.
- ROSE, A., REN, Z. F., DAY, G. W. Twisting and annealing optical fiber for current sensors. Journal of Lightwave Technology, 1996, vol. 14, no. 11, p. 2492 - 2498.
- LAMING, R. I., PAYNE, D. N. Electric current sensors employing spun highly birefringent optical fibers. Journal of Lightwave Technology, 1989, vol. 7, no. 12, p. 2084 - 2094.
- WAYNANT, R. Electro-Optics Handbook. New York: McGraw-Hill Professional, 2000.
- BORN, M., WOLF, E. Principles of Optics. Cambridge: Cambridge University Press, 1999.
- ULRICH, R., RASHLEIGH, S. C., EICKHOFF, W. Bendinginduced birefringence in single-mode fibers. Optical Letters, 1980, vol. 5, p. 273 - 275.
- TANG, D., ROSE, A. H., DAY, G. W., ETZEL, S. M. Annealing of linear birefringence in single-mode fiber coils: Applications to optical fiber current sensors. Journal of Lightwave Technology, 1991, vol. 9, no. 8, p. 1031 - 1037.
- PAVLU, M. The Suppression of Mechanical Stress Impacts in Fiber Optic Transmission Systems. Bachelor’s thesis. Brno: FEEC, Brno University of Technology, 2008.
- RIPKA, P. Magnetic Sensors and Magnetometers. London: IEEE; Artech House, 2001.
- DREXLER, P., FIALA, P. Methods for high-power EM pulse measurement. IEEE Sensors J., 2007, vol. 7, no. 7, p. 1006 – 1011.
- DREXLER, P., FIALA, P. Identifying of the special purpose generator pulses. In Proceedings of Progress in Electromagnetics International Conference PIERS 2007. Beijing (China), 2007, p. 561 – 565.

Keywords: Fiber optic sensor, magneto-optic effect, Faraday mirror, linear birefringence, circular birefringence.

**H. Blasinsky, F. Amiel, T. Ea, F. Rossant, B. Mikovicova**
[references] [full-text]

Implementation and Evaluation of Power Consumption of an Iris Pre-processing Algorithm on Modern FPGA

In this article, the efficiency and applicability of several power reduction techniques applied on a modern 65nm FPGA is described. For image erosion and dilation algorithms, two major solutions were tested and compared with respect to power and energy consumption. Firstly the algorithm was run on a general purpose processor (gpp) NIOS and then hardware architecture of an Intellectual Property (IP) was designed. Furthermore IPs design was improved by applying a number of power optimization techniques. They involved RTL level clock gating, power driven synthesis with fitting and appropriate coding style. Results show that hardware implementation is much more energy efficient than a general purpose processor and power optimization schemes can reduce the overall power consumption on an FPGA.

- RYDGREN, E., et al. Iris features extraction using wavelet packets. In IEEE Int. Conf. on Image Processing. Singapore, October 2004.
- ROSSANT, F., TORRES ESLAVA, M., EA, T., AMIEL, F., AMARA, A. Iris identification and robustness evaluation of a wavelet packets based algorithm. In ICIP’05, Genoa (Italy), 2005.
- GONZALES, R., WOODS, R. Digital Image Processing. Third edition, Prentice Hall, 2008.
- AMARA, A., AMIEL, F., EA, T. FPGA vs. ASIC for low power applications. Microelectronics Journal, July 2006, Elsevier Ltd.
- PIGUET, C. et al. Low-power Electronics Design. CRC Press, 2005.

Keywords: FPGA, power optimization, dilation, erosion, general purpose processor, SoPC.

**K. Bartusek, P. Fiala, J. Mikulka**
[references] [full-text]

Numerical Modeling of Magnetic Field Deformation as Related to Susceptibility Measured with an MR System

The possibility is studied of numerical modeling of magnetic field deformations in the environment of measured diamagnetic and paramagnetic samples for the purposes of studying magnetic resonance (MR) image deformations owing to the susceptibility of heterogeneous materials (objects). The verification was realized using a simple sample configuration (circular plate), and the numerically modeled cross-sections were compared with the experimentally obtained values of the magnetic field measured by the MR gradient echo technology. The results show that it is possible – via a technical calculation – to determine a magnetic field deformation in the environment of complex-shaped or non-homogeneous structures in the MR experiments.

- VLAARDINGERBROEK, M. T..; DEN BOER, J. A. Magnetic Resonance Imaging. Heidelberg (Germany): Springer-Verlag, 1999, ISBN 3-540-64877-1.
- SLICHTER, C. P. Principles of Magnetic Resonance. Second revised and expanded edition, corrected second printing. Berlin (Germany): Springer-Verlag, 1980.
- HAACKE, E. M.; BROWN, R. W.; THOMPSON, M. R.; VENKATESAN, R. Magnetic Resonance Imaging – Physical Principles and Sequence Design. John Wiley & Sons, 2001, ISBN 0- 471-48921-2.
- ARIMA, H. K.; MAEHATA S.; ISHIBASHI, K.; NAKAMOTO, T.; SHINTOMI, T. Multipole analysis for absolute magnetic field measured by multi-probe pulsed-NMR method. IEEE Transactions on Applied Superconductivity, March 2000, vol. 10, no. 1, pp. 1450 - 1453, ISSN 1051-8223.
- ZHANG, Z. Q., LIU, Q. H. Two nonlinear inverse methods for electromagnetic induction measurements. IEEE Transactions on Geoscience and Remote Sensing, June 2001, vol. 39 , no. 6, pp. 1331 to 1339, ISSN 0196-2892.
- MATHIEU, J.-B., BEAUDOIN, G., MARTEL, S. Method of propulsion of a ferromagnetic core in the cardiovascular system through magnetic gradients generated by an MRI system. IEEE Transactions on Biomedical Engineering, Feb. 2006, vol. 53, no. 2, pp. 292 - 299, ISSN 0018-9294.
- SUMANAWEERA, T. S., GLOVER, G. H., BINFORD, T. O., ADLER, J. R. MR susceptibility misregistration correction. IEEE Transactions on Medical Imaging, June 1993, vol. 12, no. 2, pp. 251–259, ISSN 0278-0062.
- STEINBAUER, M., KROUTILOVA, E. Measurement of weakly magnetic material using new MR technique. In Proceedings of Applied Electronics 2006. Pilsen (Czech Republic), 2006. pp. 87-91, ISBN 80-7043-442-2.
- FIALA, P., KROUTILOVA, E., STEINBAUER, M., HADINEC, M., BARTUSEK, K. Inversion reconstruction of signals measured by the NMR techniques. In Proceedings of PIERS 2007. Prague (Czech Republic), pp. 363-366, ISSN 1559-9450.
- REULET, P., NORTERSHAUSER, D., MILLAN, P. Inverse method using infrared thermography for surface temperature and heat flux measurements. In Proceedings of 20th International Congress on Instrumentation in Aerospace Simulation Facilities. Gottingen (Germany), 25-29 Aug. 2003, pp. 118 - 126. ISBN 0-7803-8149-1.
- BARTUSEK, K., DOKOUPIL, Z. Magnetic resonance diffusion measurement method in heterogenous systems. In Modern Development of Magnetic Resonance 2007. Kazan (Russian Federation): Zavoisky Physical Technical Institute Kazan, 2007. pp. 142-143.
- Houston (USA): Ansys User’s Manual. Svason Analysys System, Inc., Houston, USA, 1994-2006.

Keywords: Magnetic resonance (MR), numerical modeling, magnetic resonance imaging (MRI), magnetic field mapping, finite element method (FEM).