US Patent 7242733 Clock recovery circuit

The clock recovery circuit includes a first oscillator and an edge detector. The first oscillator generates a plurality of clocks having different phases and a predetermined frequency. The edge detector detects two clocks, among the plurality of clocks, between edges of which an input data signal has made a transition. The first oscillator includes a plurality of delay cells connected in a ring, and outputs of the plurality of delay cells are output as the plurality of clocks. Each of the plurality of delay cells selectively delays a first-delay added input data signal or the signal output from the preceding delay cell, and outputs the selected delayed signal. The edge detector controls one delay cell among the plurality of delay cells corresponding to the result of the detection, to delay and output the first-delay added input data signal.