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. 15, 1980
Filed:
Jan. 12, 1978
Michael A Clark, Crawley Down, GB;
Michael J Underhill, Faygate, GB;
U.S. Philips Corporation, New York, NY (US);
Abstract
Phase comparison apparatus, for example for use in phase lock loop (PLL) systems, comprises a first and a second phase comparator. The first comparator has a high gain (e.g. 1000) and a narrow phase difference range (e.g. 5.degree.) and the second phase comparator has a substantially greater range (e.g. 720.degree.). The second phase comparator is automatically switched out when the apparatus is operating in the narrow range and the outputs of the two comparators are proportionately combined in such a way that the combined output characteristic is linear over the whole range covered by the apparatus. The lock-up time of a PLL system using the apparatus is reduced by 10 to 100 times and system noise due to the apparatus can be reduced to negligible proportions.