| 摘要 |
PURPOSE:To detect an NRZI signal accurately, by controlling a charge pump by signals obtained by differentiating the NRZI signal and the output signal of an oscillator, respectively. CONSTITUTION:The NRZI signal detected from a digital audio disk is inputted to a circuit 10 to detect its rising and falling points. The output signal of the voltage-controlled oscillator is inputted to a terminal 20a of a phase comparing circuit 13. The phase comparing circuit 13 has differentiating circuits 22 and 23 for differentiating signals from terminals 20a and 20b. When output pulses of the differentiating circuits and the signals from the terminals 20a and 20b are present concurrently, flip-flops 30 and 31 are set and reset. By the output of the flip-flop 30, the charge pump outputs ''0'' and by the output of the flip-flop 31, it outputs ''1'' to control the voltage-controlled oscillator, generating a synchronizing signal. |
