Digital frequency and phase comparator

Abstract

A digital frequency and phase comparator for both detecting a frequency of a digital signal and the phase thereof relative to a reference signal, wherein polarity inversions of the output phase different signal and saturated characteristics of the circuit when the phase difference succeeds a predetermined value are eliminated. The inventive digital frequency and phase comparator includes a time counter, an input holding circuit for holding a first and a second count value of the time counter at two different input timings of an input signal, a first arithmetic device for determining one of the frequency and period of the inputs signal in response to the first and second count values held by the input timing holding device, and a second arithmetic device for determining a phase of the input signal relative to a reference signal in response to a selected one of the first and second count values held in the input timing holding device.

Dependencies are inferred from the claim text.