Title: Clock data recovery having a recovery loop with separate proportional path
Application Number: 200610093523 Application Date: 2006.06.26
Publication Number: 1893276 Publication Date: 2007.01.10
Approval Pub. Date: Granted Pub. Date:
International Classifi-cation: H03L7/08;H03L7/00
Applicant(s) Name: Altera Corp. Address:
Inventor(s) Name: Wang Shoujun;Mei Haitao;Bereza Bill;Kwasniewski Te
Attorney & Agent: zhao rongmin xue feng
Abstract:
    A clock data recovery loop that can be used over a wide range of data rates and maintain second-order behavior includes a nonlinear (e.g., Bang-Bang) phase detector, a charge pump, an RC loop filter, and signal generator (e.g., a voltage controlled oscillator (VCO)). At low data rates, the loop may be operated with the charge pump and loop filter with stable second-order behavior, with the resistor R of the loop filter serving as a proportional path. A separate proportional path is also provided that provides phase detector output directly to a control input of the VCO, while the resistor R of the loop filter is also bypassed. As increasing data rates give rise to third-order effects, the separate proportional path may be activated to maintain second-order behavior.
Time: 19