Miscellaneous active electrical nonlinear devices – circuits – and – Specific identifiable device – circuit – or system – Unwanted signal suppression
Patent
1995-03-17
1995-11-28
Callahan, Timothy P.
Miscellaneous active electrical nonlinear devices, circuits, and
Specific identifiable device, circuit, or system
Unwanted signal suppression
327103, 330305, H03B 500
Patent
active
054711681
ABSTRACT:
Based on the insight that the damping of a tunable filter is both related to its quality factor as to its passband gain, an inventive tuning system is proposed which tunes the quality factor of such a filter to a desired quality factor value by tuning the passband gain of the filter to a desired gain value. Such a tuning system is particularly useful in the field of OTA-C filters and consists of first (P1) and second (P2) tuning paths including such a tunable filter (BIQUAD) and fixed gain amplifiers (B-OTA1, B-OTA2). The gain of the latter amplifiers corresponds to the desired gain values. The tuning system further includes matching means (MM) for equalizing the gains in both tuning paths (P1, P2) by generating a quality factor tuning signal (VTQ) which is applied both to the tunable filter (BIQUAD) and to a replica thereof used as master filter in a data processing path. This matching means (MM) includes current rectifiers (C-REC1, C-REC2) implemented so as to use little hardware.
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patent: 5124593 (1992-06-01), Michel
"An Elliptic Continuous-Time CMOS Filter with On-Chip Automatic Tuning" by Mihai Banu et al., IEEE Journal of Solid-State Circuits, vol. SC-20, No. 6, Dec. 1985, pp. 1114-1121.
"A CMOS Transconductance-C Filter Technique for Very High Frequencies" by Bram Nauta, IEEE Journal of Solid-State Circuits, vol. 27, No. 2, Feb. 1992, pp. 142-153.
"A 10.7-MHz CMOS OTA-R-C Bandpass Filter with 68 dB Dynamic Range and on-chip Automatic Tuning", M. Steyaert et al, ISSCC, Feb. 1992, pp. 66-67.
Sevenhans Joannes M. J.
Van Paemel Mark G. S. J.
ALCATEL N.V.
Callahan Timothy P.
Le Dinh
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