PLL circuit

摘要

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.

主权项

1. A PLL circuit, comprising:
a phase comparator to detect a phase difference between a reference signal and a feedback signal; first and second charge pumps each to output a current according to a detection result of the phase comparator; a filter to output a first current obtained by removing a high frequency component of the output current of the first charge pump; an integrator to integrate the output current of the second charge pump and output an integrated voltage; a voltage-current conversion circuit to output a second current according to the integrated voltage; and an oscillator to generate an oscillating signal of a frequency according to a third current generated by adding the first and the second currents, and to feed it back to the phase comparator, wherein the filter includes a first resistance element provided in series on a first signal line in which the output current of the first charge pump flows and a first capacitative element provided between the first signal line and the first power supplywherein the integrator includes a second capacitative element provided between a second signal line in which the output current of the second charge pump flows and a second power supply.