Patent ID: 6351164
Filing Date: 2002-02-26
Classification: H03L

Abstract:
A PLL circuit for obtaining the oscillation frequency signal that is synchronized with an input signal, comprising:a voltage-controlled oscillator for oscillating at an oscillation frequency in accordance with a control signal; a phase difference detector for detecting a phase difference between the input signal and an output signal from the voltage-controlled oscillator; a loop filter for outputting said control signal based on an output signal of the phase difference detector; a frequency error detector for detecting error of the oscillation frequency by comparing the output signal of said voltage-controlled oscillator with a reference signal; an adder for adding said frequency error to said control signal; and a first multiplier for multiplying the control signal from said loop filter with a first coefficient and a second multiplier for multiplying the output signal of said frequency detector with a second coefficient, wherein an output of the first multiplier and an output of the second multiplier are added by said adder, and said control signal is adjusted in accordance with the error of the frequency detected by said frequency error detector and supplied to said voltage-controlled oscillator.