Patent ID: 6222421
Filing Date: 2001-04-24
Classification: H03L

Abstract:
A phase-locked loop comprising:a voltage-controlled oscillator for generating an oscillation output signal having a frequency corresponding to a control voltage;a phase comparator connected to the voltage-controlled oscillator for comparing a phase of the oscillation output signal and a phase of a reference clock signal to generate a comparison output signal;a first charge pump circuit connected to the phase comparator for generating a first charge pump output signal in accordance with the comparison output signal;a first low-pass filter connected to the first charge pump circuit for smoothing the first charge pump output signal and generating the control voltage;a second charge pump circuit for generating a second charge pump output signal;a second low-pass filter connected to the second charge pump circuit for smoothing the second charge pump output signal and generating a compensation voltage; anda control circuit connected to the second low-pass filter for controlling the first and second charge pump circuits to adjust the first and second charge pump output signals in accordance with the compensation voltage.