Title: Phase and frequency detection circuits
Application Number: 200610079803 Application Date: 2006.05.08
Publication Number: 1909376 Publication Date: 2007.02.07
Approval Pub. Date: Granted Pub. Date:
International Classifi-cation: H03L7/089;H04L7/033
Applicant(s) Name: Realtek Semiconductor Corp. Address:
Inventor(s) Name: Hsieh Hong-yean
Attorney & Agent: huang xiaolin wang zhisen
Abstract:
    In one embodiment, a phase-locked loop system in a receiver samples received incoming data using a first clock and a second clock that have the same frequency but are out of phase with each other. A first control signal generated by a phase detector is used to control a charge pump, whose output may be filtered to drive a VCO circuit generating the first and second clocks. A frequency detector generates a second control signal based at least on phase relationships between the incoming data and the first and second clocks. A qualifier circuit determines if the first control signal is valid or invalid based at least on the second control signal.
Time: 13
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