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:
Jan. 10, 1989
Filed:
Aug. 31, 1987
Paul D Filliman, Indianapolis, IN (US);
RCA Licensing Corporation, Princeton, NJ (US);
Abstract
A controlled crystal oscillator of a stereo decoder of a television receiver using CMOS technology includes first, second and third differential emplifiers that produce corresponding first, second and third pairs of anti-phase output signals. The first and second differential amplifiers have variable gains that vary in opposing manners in accordance with a frequency control signal. The oscillatory signal of a crystal is coupled to corresponding input terminals of the three differential amplifiers such that the phase of the signal that is developed at the input terminal of the third differential amplifier is phase-shifted by approximately 90.degree. relative to those developed at the input terminals of the other two amplifiers. The three pairs of output signals are combined to form a single-ended oscillatory signal that is coupled back to the crystal to complete a regulative feedback path. The frequency of oscillation is determined in accordance with the frequency control signal.