Miscellaneous active electrical nonlinear devices – circuits – and – Specific identifiable device – circuit – or system – Unwanted signal suppression
Patent
1998-12-15
2000-09-19
Le, Dinh T.
Miscellaneous active electrical nonlinear devices, circuits, and
Specific identifiable device, circuit, or system
Unwanted signal suppression
327552, 327332, 348665, H03K 500
Patent
active
06121826&
ABSTRACT:
A comb filter easily implementable as a monolithic LSI without using a large-capacitance capacitor is provided. A comb-like frequency characteristic is realized by two delay circuits for delaying a signal for mutually different amounts of time and an operation circuit for deriving a sum or difference of the outputs thereof. An input select switch selectively outputs, instead of an image signal, a test signal, which is a DC signal having a predetermined amplitude, during a blanking interval of the image signal. A detector controls the gain of a variable-gain amplifier, provided for the output of either one of the delay circuits, in accordance with a difference between the output signal of the comb filter in response to the test signal and a predetermined reference signal. That is to say, the gain of the comb filter is controlled by using a stable test signal as a control signal, instead of a burst signal contained in an unstable image signal. Accordingly, a large-capacitance capacitor, which has been required for stabilizing the control signal, is no longer necessary.
REFERENCES:
patent: 5523798 (1996-06-01), Hagino et al.
Kazuyuki Matsui et al., "CMOS Video Filters Using Switched Capacitor 14-MHz Circuits", IEEE Journal of Solid-State Circuits, vol. SC-20, No. 6, Dec. 1985, pp. 1096-1101.
Patent Abstracts of Japan, vol. 14, No. 151, (E-906), Mar. 22, 1990 & JP 02 010993 A, Published. Jan. 16, 1990 (Hitachi).
Dosho Shiro
Kurimoto Hidehiko
Okamoto Tatsuo
Ozasa Masayuki
Yanagisawa Naoshi
Le Dinh T.
Matsushita Electric - Industrial Co., Ltd.
Robinson Eric J.
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