Patent ID: 7333570
Filing Date: 2008-02-19
Classification: G11C,H03L,H03M,H04L

Abstract:
1. Circuitry for recovering clock information from a clock data recovery (CDR) signal comprising: receiver circuitry for receiving the CDR signal and an external reference clock signal; first circuitry for producing from the external reference clock signal a plurality of differently phase-shifted candidate recovered clock signals; and second circuitry for producing a recovered clock signal based on a selection from among the candidate recovered clock signals, the selection being based on a digitalized comparison between phases of transitions in the CDR signal and the recovered clock signal, and wherein the second circuitry maintains the selection it has made until subsequent transitions in the CDR signal have closer proximity to transitions in another of the candidate recovered clock signals, so that during an absence in CDR signal transitions, no change is made in the selection.