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:
Mar. 13, 1990
Filed:
Mar. 29, 1989
Applicant:
Inventors:
Mitsumo Kawano, Kumagaya, JP;
Tadashi Terada, Fukaya, JP;
Assignee:
Kabushiki Kaisha Toshiba, Kawasaki, JP;
Attorney:
Primary Examiner:
Int. Cl.
CPC ...
H03L / ;
U.S. Cl.
CPC ...
331 / ; 331 14 ; 331 17 ; 331 20 ; 331 27 ; 358158 ; 328134 ; 328155 ;
Abstract
An AFC circuit using counters, flip-flops and logic gates produces a first pulse signal only when the phase of a VCO output signal lags the phase of a reference signal, and produces a second pulse signal only when the phase of the VCO output signal leads the phase of the reference signal. The first and second pulse signals control a switch to connect a first or a second constant current source to charge or discharge a filter circuit, to thereby produce a control voltage for the VCO. When the VCO output signal is in phase with the reference signal, the switch remains in a neutral position to hold a constant control voltage on the filter.