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:
Dec. 04, 1990
Filed:
Aug. 29, 1989
Richard A Kennedy, Russiaville, IN (US);
Seyed R Zarabadi, Columbus, OH (US);
Delco Electronics Corporation, Kokomo, IN (US);
Abstract
An integrated circuit FM detector which compensates for variations in semiconductor manufacturing process and temperature employs a pair of serially connected switched capacitor-operational amplifier combinations. The first combination is a frequency to voltage converter which uses a switched capacitor input circuit which is clocked at the frequency of the input signal, an operational amplifier and a feedback resistor. The second combination is a compensation circuit which uses an input resistor, a feedback switched capacitor circuit and an operational amplifier. The feedback switched capacitor circuit is clocked at a fixed rate. Reversal of the roles of the resistor and the switched capacitor in the first and second combinations compensates for both temperature and manufacturing process variations. The electrical separation of the input and feedback switched capacitor circuits helps to insure against the generation of unwanted noise in the form of beat frequencies which could be generated if the switched capacitor circuits were used as the input and feedback circuits of a single operational amplifier.