Phase comparator circuit

A phase detector circuit that outputs a signal including a DC voltage component associated with a phase difference between two input signals, comprising:

• a delay circuit for outputting a signal delayed by the time of (T−δT), which is shorter than the period T of an input random NRZ signal;
• a subtracter circuit for outputting a difference between said input random NRZ signal and the signal delayed by said delay circuit;
• a multiplier circuit for outputting a product of another input random NRZ signal having the same pattern as that of said input random NRZ signal and said phase difference and an output of said subtracter circuit.

A phase detector circuit that receives a random NRZ signal Vi(t) having a period of T and a signal Vi(t−θT/2π) having the same period and pattern as those of the signal Vi(t) and delayed from the signal Vi(t) by θ in phase, and outputs a signal including a DC voltage component associated with a phase difference θ between said two signals,

• wherein an output Vo(t) of the phase detector circuit is represented by:
• Vo(t)=(Vi(t)−Vi(t−(T−δT)))×Vi(t−θT/2π),
• where the signal Vi(t−(T−δT)) is delayed from the signal Vi(t) by the time of (T−δT), which is shorter than the period T of the signal Vi(t).

A phase detector circuit that outputs a DC voltage signal associated with a phase difference between an input random NRZ signal and a second signal related to said input random NRZ signal, comprising:

• a delay circuit for delaying said input random NRZ signal by an amount related to a period T of said input random NRZ signal and outputting a delayed signal;
• and
• a combination of at least one multiplier circuit and a subtracter circuit, which combination performs an arithmetic operation on only said input random NRZ signal, said delayed signal, and said second signal to produce an output signal having a DC voltage component corresponding to said phase difference.