| 摘要 |
PURPOSE:To facilitate the recovery of synchronization by giving an output of a loop filter to an amplitude detection circuit and inputting an output of the amplitude detection circuit to a resistor connected to a power voltage and a control terminal of a voltage controlled oscillator. CONSTITUTION:An output voltage of a loop filter 3 is a positive voltage in the locking state, the output voltage of the loop filter 3 becomes an output of an amplitude detection circuit 11 and fed to a control terminal of the voltage controlled oscillator 9 to keep the locking state. On the other hand, if the locking is lost at application of power and the output voltage of the loop filter 3 is a negative voltage, the negative voltage of the loop filter 3 is not fed to the control voltage of the voltage controlled oscillator 9 by a diode 4 of the amplitude detection circuit 11 and a voltage rising gradally up to the power voltage from zero V as a start is fed to the control terminal of the voltage controlled oscillator by a resistor 6. Thus, the synchronization is recovered easily. |
