Abstract: A PLL circuit includes: a phase comparator for detecting a phase difference between a reference signal and a feedback signal; a first charge pump for outputting a current Ipr according to a detection result of the phase comparator; a second charge pump for outputting a current Iint according to the detection result of the phase comparator; a filter for outputting a current Iprop from which a high frequency component of the Ipr is removed; an integrator for integrating the Iint; a voltage-current conversion circuit for outputting a current Ivi according to an integrated result of the integrator; and an oscillator that generates an oscillating signal of a frequency according to a current Iro, a sum of the Iprop and the Ivi, and feeds it back to the phase comparator.

Abstract: A PLL circuit includes: a phase comparator for detecting a phase difference between a reference signal and a feedback signal; a first charge pump for outputting a current Ipr according to a detection result of the phase comparator; a second charge pump for outputting a current Iint according to the detection result of the phase comparator; a filter for outputting a current Iprop from which a high frequency component of the Ipr is removed; an integrator for integrating the Iint; a voltage-current conversion circuit for outputting a current Ivi according to an integrated result of the integrator; and an oscillator that generates an oscillating signal of a frequency according to a current Iro, a sum of the Iprop and the Ivi, and feeds it back to the phase comparator.

Abstract: A PLL circuit includes: a phase comparator for detecting a phase difference between a reference signal and a feedback signal; a first charge pump for outputting a current Ipr according to a detection result of the phase comparator; a second charge pump for outputting a current Iint according to the detection result of the phase comparator; a filter for outputting a current Iprop from which a high frequency component of the Ipr is removed; an integrator for integrating the Iint; a voltage-current conversion circuit for outputting a current Ivi according to an integrated result of the integrator; and an oscillator that generates an oscillating signal of a frequency according to a current Iro, a sum of the Iprop and the Ivi, and feeds it back to the phase comparator.

Abstract: In a clock generating circuit, while a PLL (Phase-Locked Loop) circuit and a modulator are employed, when a frequency dividing ratio of a feedback-purpose frequency divider in the PLL circuit is changed in accordance with modulation data produced based upon a modulation profile of the modulator to perform a frequency modulation so as to spread a spectrum, a turning point of the modulation profile is moved so as to disperse a degree of frequency, so that the spread spectrum is re-spread. Also, a clock generating circuit is constituted by a PLL circuit and a modulator, a multiple modulation profile generating circuit is provided in the modulator, and a turning point of a modulation profile is moved so as to disperse a degree of frequency, so that a spread spectrum is re-spread.

Abstract: In a clock generating circuit, while a PLL (Phase-Locked Loop) circuit and a modulator are employed, when a frequency dividing ratio of a feedback-purpose frequency divider in the PLL circuit is changed in accordance with modulation data produced based upon a modulation profile of the modulator to perform a frequency modulation so as to spread a spectrum, a turning point of the modulation profile is moved so as to disperse a degree of frequency, so that the spread spectrum is re-spread. Also, a clock generating circuit is constituted by a PLL circuit and a modulator, a multiple modulation profile generating circuit is provided in the modulator, and a turning point of a modulation profile is moved so as to disperse a degree of frequency, so that a spread spectrum is re-spread.