| 摘要 |
PROBLEM TO BE SOLVED: To provide a phase synchronization circuit having a pull-in circuit, in which the lock range can be enlarged and a locked state can be maintained stably. SOLUTION: The phase synchronization circuit has a signal path, where a phase comparator, a loop filter and a voltage-controlled oscillator are cascaded. The phase comparator compares the phase between an input signal and an output signal from the voltage-controlled oscillator, and outputs the comparison results. The loop filter receives an output signal from the phase comparator and outputs a DC voltage, and the voltage-controlled oscillator controls the output oscillation frequency, depending on the DC output voltage from the loop filter. The phase synchronization circuit adds a signal for matching the average output voltage from the phase comparator with a prescribed reference voltage to the voltage of the signal path. |
