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:
Oct. 26, 1999
Filed:
Mar. 27, 1998
Yasuhiro Fujii, Kawasaki, JP;
Fujitsu Limited, Kawasaki, JP;
Abstract
In the present invention, when a phase comparison circuit, which compares the phase of a reference clock divided by a frequency divider that frequency divides a supplied clock, to that of a variable clock, detects the phase-matching of the two clocks, it generates a phase synchronization detection signal, and this phase synchronization detection signal increases the frequency division ratio of a frequency divider, lowering the frequency of operation of the phase comparator. The present invention is further characterized in that, at reset, when an inactive state becomes an active state, the time required to phase synchronize both clocks is shortened by resetting the above-described phase synchronization detection signal, thereby setting the frequency division ratio of the frequency divider to its original low state, and the frequency of operation of the phase comparator to its original high state. In accordance with the above-described invention, when phase synchronization is detected in an active state, the frequency division ratio of the frequency divider is increased, and the frequency of operation of the phase comparator is lowered, thus curbing power consumption. Then, at reset, this phase synchronization detection signal is reset, thus returning the frequency division ratio of the frequency divider to its original low state, and raising the frequency of phase comparator operation.