Patent ID: 7027741

Claim:
A phase lock loop circuit, comprising: a space-to-mark transition probability detecting unit detecting a space-to-mark transition-probability of an input signal by using only the input signal, wherein the input signal is a pulse; and an adjusting unit adjusting an output of a phase comparator according to the space-to-mark transition-probability detected by said space-to-mark transition-probability detecting unit so that an output of a voltage controlled oscillator has a predetermined frequency and phase, wherein the phase comparator comprises: a phase signal detecting unit for output according to a phase difference between the input signal and the output of the voltage controlled oscillator, and a reference unit for outputting a reference signal of a fixed value according to the input signal; and said adjusting unit adjusts an output pulse of the phase signal detecting unit and an output pulse of the reference unit according to the space-to-mark transition-probability detected by said space-to-mark transition-probability detecting unit so that a product of an amplitude and a time of the output pulse of the phase signal detecting unit and a product of an amplitude and a time of the output pulse of the reference unit are equal to each other.