| 摘要 |
A clock recovery circuit which has a transition detector connected to the incoming data stream. An output of the transition detector is connected to a gate, such as a D flip-flop, which has an input receiving the recovered clock. A zero or one output will be generated depending upon whether the transition is before or after the rising edge of the recovered clock. An accumulator circuit accumulates a count for each transition, providing the results to a comparison circuit. The comparison circuit compares the accumulated count to maximum and minimum thresholds, and provides advance or retard outputs when those thresholds are exceeded. A phase circuit adjusts the phase of the recovered clock by advancing or retarding it after a sufficient number of transitions have been detected either in advance or behind the recovered clock to justify such an adjustment.
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