Patent ID: 6545546
Filing Date: 2003-04-08
Classification: H03D,H03L,H04L

Abstract:
A PLL circuit, comprising:an oscillator for generating an oscillation frequency signal having a variable oscillation frequency; a signal generation circuit for generating, based on the oscillation frequency signal of said oscillator, a first signal having a phase same as that of the oscillation frequency signal, a second signal having a fixed phase difference from the first signal, and a third signal having a phase difference smaller than the phase difference between the first and second signals from the first signal; a phase detection circuit for comparing the phases of the third signal generated by said signal generation circuit and an input signal and outputting, based on a result of the comparison, a first phase control signal for advancing the phase of the oscillation frequency signal of said oscillator or a second phase control signal for delaying the phase of the oscillation frequency signal of said oscillator; and a frequency detection circuit for fetching the first and second signals generated by said signal generation circuit in synchronism with the input signal and outputting, based on the fetched signals, a first frequency control signal for raising the frequency of the oscillation frequency signal of said oscillator or a second frequency control signal for lowering the frequency of the oscillation frequency signal of said oscillator.