The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Aug. 28, 1990
Filed:
Sep. 22, 1989
Kenneth W Moulding, Horley, GB;
U.S. Philips Corporation, New York, NY (US);
Abstract
A filter circuit (2) is automatically tuned so that the positions of the poles and zeros of its frequency response characteristic are maintained in substantially fixed ratios to an input frequency (f.sub.r). The arrangement comprises a frequency discriminator (1) having its output (5) coupled to a controllable element (8) of a resonant circuit included therein, so that the resonant frequency of the resonant circuit is maintained equal to the input frequency. The output 5 also controls a counterpart (13) to element (8), which counterpart is included in an auxiliary circuit (3). The filter circuit is tuned by controlling an element (10) included therein, which element also has a counterpart element (14) included in the auxiliary circuit, both of these elements (10,14) being controlled by the auxiliary circuit output signal. The auxiliary circuit output signal is determined by the ratio between parameters of the respective counterpart elements (13,14), which correspond to parameters of the tuning elements (8,10) which govern the tuning frequencies, and acts to maintain this ratio, and hence the aforementioned ratios, substantially constant.