Phase locked loop having a voltage source responsive to a filtered phase difference output voltage and semiconductor device including the phase locked loop

摘要

A phase locked loop having a charging pump circuit portion for generating a phase difference output voltage between an input signal and an oscillation output signal, and a semiconductor device including such a phase locked loop, are constituted so that the phase difference output signal from the charging pump circuit portion is inputted to a voltage controlled oscillator through a low-pass filter, and an oscillation frequency of the oscillation output signal from the voltage controlled oscillator is brought into conformity with a frequency of the input signal, and they further include voltage source means which is connected to a phase difference output terminal of the charging pump circuit portion during each period in which the phase difference output terminal of the charging pump circuit portion is in a non-conductive state, and supplies a voltage having a potential substantially equal to the potential of the low-pass filter on the output side thereof.