| 摘要 |
PURPOSE:To expand a capture range by synchronizing a clock signal in accordance with the speed change of the reproduced signal of an input digital signal. CONSTITUTION:A phase comparator 1 detects the phase difference between an input digital signal A and a clock signal CK and outputs a phase difference signal B proportional to the phase difference value and a variable frequency oscillator 2 outputs a clock signal CK having frequency fCK proportional to the signal B. A saw tooth wave generating circuit consisting of an edge detecting circuit 3, a counter 4 and a D/A converter 5 changes the speed in accordance with the frequency of the signal CK and holds the peak value of the output in a peak holding circuit 6. A differential amplifier 7 sends a signal obtained by adding/ subtracting the signal B to/from an output signal from the circuit to the oscillator 2, so that even if the speed of the signal B is changed, the clock signal CK synchronized with the signal B is easily oscillated from the oscillator 2. |
