Patent ID: 8111798

Claim:
A phase synchronization circuit comprising: a controlled oscillator configured to generate a first oscillation signal and a second oscillation signal that have a common frequency but different phase controlled by a combination of a first control signal and a second control signal; a digital phase frequency detector configured to detect a frequency difference and a first phase difference between a reference signal and the first oscillation signal to generate a first detection signal that accords with the frequency difference and the first phase difference; a digital filter configured to suppress high-frequency components of the first detection signal to obtain the first control signal; an analog phase detector configured to detect a second phase difference between the second oscillation signal and the reference signal to generate a second detection signal that accords with the second phase difference; an analog filter configured to perform a filtering process to suppress high-frequency components of the second detection signal to obtain a filtered signal; an amplifier configured to amplify the filtered signal to obtain the second control signal; and a lock detection unit configured to detect a lock of the first oscillation signal with the reference signal in terms of frequency and phase, in order to set the analog phase detector, the analog filter and the amplifier in an active state.