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. 12, 1989
Filed:
Aug. 24, 1987
Michael F Black, Garland, TX (US);
Texas Instruments Incorporated, Dallas, TX (US);
Abstract
Apparatus and method for verifying the lock state or lock condition of a phase locked loop that includes a phase detector, a loop filter and a voltage controlled oscillator. The apparatus comprises a second oscillator that provides a signal of predetermined frequency to the loop filter and a second phase detector providing an output signal indicative of phase lock status. According to the method a signal of predetermined frequency is input to the loop filter and to a second phase detector. The presence of signals to the predetermined frequency is detected at the output of the loop phase detector by inputing the output from the loop phase detector to the second phase detector.