System for unambiguously determining the phase of an input signal of

Abstract

A clocked digital signal processing system includes apparatus for unambiguously indicating the phase of an input signal relative to a reference clock signal. In particular, the disclosed apparatus reduces timing uncertainty between the reference clock, and the output signal of a phase detector representing the phase relationship between the input signal and the reference clock. A phase detector including a logic network provides plural comparison signals representing a phase relationship between the input and reference signals. The comparison signals are conveyed via first and second latch circuits, in respective groups, to a clocked downstream stage. The first and second latch circuits are clocked by different phases of the reference clock and provide outputs synchronous with the reference clock. The downstream stage responds to the reference clock for conveying output signals front the first and second latch circuits to an output at which the unambiguous indication appears.