Phase detector capable of detecting an accumulated value of phase displacement at a high speed and frequency stability measuring apparatus for arbitrary nominal frequency using the same

Abstract

A phase region detector receives in-phase signal I representing in-phase component and quadrature signal Q representing quadrature component of a first signal and second signal respectively, equally divides an angle range of 2 π into a plurality M of three or more of angle regions preliminarily, on virtual quadrature coordinates, sequentially assigns angle region numbers in each of the angle regions, detects the angle region corresponding to the variation of phase of the second signal starting from the phase of the first signal, and issues the angle region number assigned in this angle region. A phase displacement detector issues a signal expressing the time change of the variation of the phase from the change corresponding to the time of the angle region number. An out-of-bounds detector receives a signal issued from the phase displacement detector, and issues an out-of-bounds signal including the out-of-bounds direction every time the variation of the phase exceeds a predetermined value. A phase rotation counter issues the number of rotations of the phase by accumulating the out-of-bounds signals. A displacement accumulator determines the cumulative value of phase displacement determined by the in-phase signal I and quadrature signal Q, based on the angle region number, the number of angle regions, and the number of rotations of the phase.