| 摘要 |
PURPOSE:To shorten the time for reproducing a clock by switching a control voltage of a voltage control oscillator of a phase locked circuit to a prescribed constant-voltage, when circuit disconnection has been detected. CONSTITUTION:When a circuit is disconnected, a level detector 8 detects it, connects a switch SW to a dotted line side, and switches a control voltage of a voltage control oscillator 7 to a prescribed voltage V. The prescribed voltage V is a control voltage derived in advance for setting a frequency of a clock of the voltage control oscillator 7 to the almost same frequency of a clock of receiving data, therefore, the frequency of the clock of the voltage control oscillator 7 is almost equal to the clock of the receiving data, even if it is switched. Accordingly, when the switch SW is connected to a full line side, the frequency and phase of the clock of the voltage control oscillator 7 become immediately those which are equal to the clock of the receiving data, and the time for reproducing a clock is shortened remarkably. |
