| 摘要 |
PURPOSE:To allow a phase locked loop to lock in phase again after a fixed period by interrupting and holding the output of a loop filter in the phase locked loop for the fixed period at the instantaneous out-of-phase. CONSTITUTION:Voltage due to the phase difference between the phase of an input signal 1 to the phase locked loop and the phase of an output from a voltage controlled oscillator 2 is outputted from a phase comparator 3. The output of the comparator 3 is applied to the oscillator 2 as a control voltage so that the phase difference is turned to zero by the loop filter 4. If the phase locked loop goes to out-of-phase, a switch 8 is turned off by a phase locking detecting part 9 to interrupt the output of the filter 4 and the output of the filter 4 is held for the fixed period (t) by a holding circuit 5. When the lock-off status is generated for the fixed period of instantaneously, the loop filter is held for the fixed period (t), so that the phase locking of the phase locked loop is restored again after the fixed period (t). |
