PLL circuit and optical communication reception apparatus

An optical communication reception apparatus, comprising:

• light reception means for receiving an optical signal, converting the optical signal into an electric signal and outputting the electric signal;
• a PLL circuit for producing a clock signal synchronized with the output signal of said light reception means;
• and
• a retiming circuit for retiming the output signal of said light reception means based on the clock signal produced by said PLL circuit;
• said PLL circuit including 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.