PLL circuit

A PLL circuit comprising

• an oscillator that outputs an oscillation signal at a frequency corresponding to a control signal,
• a frequency divider of a fractional frequency division system that divides and outputs the oscillation signal,
• a reference signal generator that generates a reference signal,
• a phase comparator that compares the phase of the signal output from said frequency divider and that of the reference signal and outputs a first signal and a second signal corresponding to the phase difference,
• a charge pump circuit that has a first current supply circuit, which supplies to the output terminal a first current corresponding to the first signal, and a second current supply circuit, which supplies to the output terminal a second current corresponding to the second signal,
• a capacitive element that is connected to the output terminal of the charge pump circuit,
• a low-pass filter that takes the signal from the output terminal of the charge pump circuit as its input and supplies the control signal to the oscillator,
• a switch element that is connected between the output terminal of the charge pump circuit and the input terminal of the low-pass filter,
• and a compensating circuit that supplies a compensating current to the input terminal of the low-pass filter for removing the ripple component contained in the signal of the output terminal of the charge pump circuit;
• whereby, when the PLL circuit is in the locked state, supply of the first current and supply of the second current start at different times, and these supplies are stopped at the same time.