Patent ID: 8031015

Claim:
A PLL circuit comprising: an oscillation circuit that generates an oscillation signal with an oscillation frequency based on a supplied voltage; a frequency divider that divides the frequency of the oscillation signal based on a predetermined frequency dividing number to generate a comparison signal; a phase comparator configured to generate a phase difference signal indicative of a phase difference between the generated comparison signal and a reference signal; a low-pass filter that generates a voltage signal formed as a direct current from the phase difference signal and that supplies the voltage signal to the oscillation circuit; a controlling unit that causes spreading of a power spectrum of the oscillation signal by switching, at a predetermined timing, the phase comparator between a first state where the phase difference signal is output from the phase comparator and a second state where the phase difference signal is disabled and not output from the phase comparator; and a resistor element that is disposed between a predetermined potential and a signal line for supplying the phase difference signal from the phase comparator to the low pass filter, when the phase difference signal is output from the phase comparator, the oscillation circuit performing oscillation operation based on the voltage signal corresponding to the phase difference signal, when the phase difference signal is disabled, the low pass filter being supplied with the predetermined potential through the resistor element to allow the oscillation circuit to perform oscillation operation based on the voltage signal generated depending on the supplied predetermined potential.