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:
Apr. 20, 1976
Filed:
Apr. 18, 1975
Applicant:
Inventors:
Takao Hara, Kawasaki, JA;
Yukio Murayama, Kawasaki, JA;
Assignee:
Fujitsu Ltd., Kawasaki, JA;
Attorney:
Primary Examiner:
Int. Cl.
CPC ...
H03B / ;
U.S. Cl.
CPC ...
331 / ; 331 12 ; 331 25 ;
Abstract
A signal detection circuit for determining synchronism and asynchronism in a phase synchronization circuit having a loop consisting of a first phase detector, a loop filter and a voltage controlled oscillator, has a second phase detector for input signals of the phase synchronization circuit and output signals of the voltage controlled oscillator. The output of the second phase detector is supplied to a low pass filter and a level judgment circuit. The level judgment circuit includes a Schmitt trigger circuit with two threshold levels due to hysteresis effect to reduce misjudgments when the input signals are low signal to noise signals.