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. 10, 2001
Filed:
Aug. 22, 1997
Ian Kyles, West Linn, OR (US);
LSI Logic Corporation, Milpitas, CA (US);
Abstract
A clock and data recovery circuit for use in a serial data communications channel includes two phase-locked loops, the two PLLs being coupled together through the use of a matched pair of voltage controlled oscillators. Each of the matched pair of oscillators includes both coarse and fine adjustment inputs. The first loop generates a first frequency based upon a reference clock input and provides a coarse tuning signal, based on the first frequency, to the second loop circuit. The second VCO drives the second loop circuit at the same frequency as the first circuit, while the second circuit is also coupled to the incoming data stream so as to provide the fine adjustment input to the second VCO. In this way, the second VCO, i.e., the second loop, is synchronized to the data, yet it remains synchronized to the reference frequency even during relatively long periods of time during which transitions in the data stream are infrequent.