| 摘要 |
PROBLEM TO BE SOLVED: To make the operation stable by masking a noise pulse in the case of outputting a signal phase-locked to a compared input signal. SOLUTION: The phase locked loop is provided with a phase comparator 1 that compares phases of a compared input signal and a comparing input signal by means of a leading or trailing edge, a charge pump section 2 that receives a lead phase comparison output signal and a phase lag comparison output signal from the phase comparator 1, a low pass filter 3 that receives an output signal of the charge pump section 2, and a voltage controlled oscillator 4 that receives an output signal of the low pass filter 3 as a control voltage and also with a noise protection circuit 6 consisting of a monostable multivibrator or a counter or the like that masks a noise pulse superimposed on the compared input signal Fr to provide the resulting pulse to the phase comparator 1. |
