Miscellaneous active electrical nonlinear devices – circuits – and – Specific identifiable device – circuit – or system – Unwanted signal suppression
Patent
1994-12-07
1995-08-08
Callahan, Timothy P.
Miscellaneous active electrical nonlinear devices, circuits, and
Specific identifiable device, circuit, or system
Unwanted signal suppression
327552, 330305, H03B 500
Patent
active
054402646
ABSTRACT:
Based on the insight that the voltage-to-current ratio or gain of a capacitor (Z) at a particular reference frequency is the product of its capacitance value with said reference frequency, a tuning system is disclosed which tunes the center frequency of an analog bandpass filter by tuning the characteristic integrator frequency (fc) of an OTA-C integrator by making the transconductance of the operational transconductance amplifier (OTA) thereof equal to the aforementioned gain at that characteristic frequency. Therefore, the tuning system includes a first tuning path in which the OTA, (or a replica thereof) is included and a second tuning path including another amplifier (B-OTA) "degenerated" by the capacitor (Z) so as to produce the required gain. The gains of both these tuning paths are then equalized by matching means (MM) generating a frequency tuning signal (VTF) which is applied to both OTA and OTA-C.
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Sevenhans Joannes M. J.
Van Paemel Mark G. S. J.
ALCATEL N.V.
Callahan Timothy P.
Le Dinh
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