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:
Sep. 04, 1990
Filed:
Apr. 12, 1989
Para Segaram, Campbell, CA (US);
Sundstrand Corporation, Rockford, IL (US);
Abstract
A tunable filter (66) having a filter characteristic tracking an input signal in accordance with the invention includes a signal source (18) providing a variable frequency signal to be tracked by the filter characteristic; a frequency detector (62) coupled to the signal source for producing a detector output signal which is a function of the frequency of the variable frequency signal; a switching signal generator (64), responsive to the frequency detector output signal, for generating at least one switching signal having a variable frequency proportional to the detector output signal; a first capacitor (112, 126, 150, 152, 156 and 158) having a first terminal coupled to a reference potential and a second terminal; and a first switching circuit (114, 128, 154 and 160) having an input coupled to the variable frequency signal, responsive to the at least one switching signal, and in response to changes in level of the at least one switching signal alternately connecting the input of the first switching circuit to the second terminal of the first capacitor and the second terminal of the first capacitor to the output of the first switching circuit coupled to an output of the filter.