Cognitive and encrypted communications, part 2 : A new approach to active frequency-agile filters and validation results for an agile bandpass yopology in SiGe-BiCMOS

A new theory for a 2nd-order frequency-agile filter is introduced in this paper. The center frequency of the filter is proportional to the gain of a feedback amplifier and thus can be tuned over a wide frequency range. This new theory is thereafter generalized to the nth-class leading to a center frequency proportional to (A)n/2. The resulting filters make use of the minimum passive elements for 2nd-order filters: two capacitors. Simulation results of band pass agile filters in current mode and made from second-generation current controlled conveyors (CCCIIQ) in 0.25¿m SiGe BiCMOS technology are given for n=1 and n=2. These simulation results along with results of measurements carried out on the fabricated filters entirely confirm the new approach. They also highlight the improvements to be expected for cognitive and encrypted communications.

[1]  Mohammed Ismail,et al.  RF bandpass filter design based on CMOS active inductors , 2003, IEEE Trans. Circuits Syst. II Express Briefs.

[2]  Alain Fabre,et al.  Current-mode band-pass filters with Q-magnification , 1996 .

[3]  A. Fabre,et al.  Low power current-mode second-order bandpass IF filter , 1997 .

[4]  K. Smith,et al.  A second-generation current conveyor and its applications , 1970, IEEE Transactions on Circuit Theory.

[5]  Alain Fabre,et al.  High-frequency high-Q BiCMOS current-mode bandpass filter and mobile communication application , 1998, IEEE J. Solid State Circuits.

[6]  D. Flandre,et al.  Fully Integrated High-Q Switched Capacitor Bandpass Filter with Center Frequency and Bandwidth Tuning , 2007, 2007 IEEE Radio Frequency Integrated Circuits (RFIC) Symposium.

[7]  A. Fabre,et al.  High frequency applications based on a new current controlled conveyor , 1996 .

[8]  A. Fabre,et al.  Dual translinear voltage/current convertor , 1983 .

[9]  J.W. Haslett,et al.  2 GHz Automatically Tuned Q-Enhanced CMOS Bandpass Filter , 2007, 2007 IEEE/MTT-S International Microwave Symposium.

[10]  Yannis Tsividis,et al.  A Si 1.8 GHz RLC filter with tunable center frequency and quality factor , 1996, IEEE J. Solid State Circuits.

[11]  A.A. Abidi,et al.  The Path to the Software-Defined Radio Receiver , 2007, IEEE Journal of Solid-State Circuits.

[12]  S. Wong,et al.  Physical modeling of spiral inductors on silicon , 2000 .

[13]  S.P. Voinigescu,et al.  30-100-GHz inductors and transformers for millimeter-wave (Bi)CMOS integrated circuits , 2005, IEEE Transactions on Microwave Theory and Techniques.

[14]  Koenraad Van Schuylenbergh,et al.  High Q RF coils on silicon integrated circuits , 2003, SPIE MOEMS-MEMS.

[15]  Balwant Godara,et al.  Versatile wideband impedance matching circuit based on current conveyors , 2007 .

[16]  Gordon W. Roberts,et al.  All current-mode frequency selective circuits , 1989 .

[17]  A. Fabre,et al.  Cognitive and encrypted communications, Part 1 : State of the art for frequency-agile filters , 2009, 2009 International Conference on Electrical and Electronics Engineering - ELECO 2009.

[18]  A. S. Sedra,et al.  The current conveyor: history and progress , 1989, IEEE International Symposium on Circuits and Systems,.

[19]  B. Razavi,et al.  Stacked inductors and transformers in CMOS technology , 2001, IEEE J. Solid State Circuits.

[20]  P. Russer,et al.  0.8 GHz to 2.4 GHz Tunable Ceramic Microwave Bandpass Filters , 2007, 2007 IEEE/MTT-S International Microwave Symposium.

[21]  Gabriel M. Rebeiz,et al.  A 25–75-MHz RF MEMS Tunable Filter , 2007, IEEE Transactions on Microwave Theory and Techniques.