Patent ID: 6486716
Filing Date: 2002-11-26
Classification: H03L

Abstract:
A phase compensation circuit comprising:three variable delay circuits whose output signal phases differ from each other by a specified phase difference; a switching circuit that selects one variable delay circuit from among said three delay circuits; a first comparator that compares a feedback signal representative of a phase of an output signal of said one selected variable delay circuit to the phase of a specified reference signal; a second comparator that compares the phases of the output signals of said three variable delay circuits to each other; and a control circuit that, based on the results of the comparison by said second phase comparator, controls delay times of one of non-selected two variable delay circuits so that the phase of the output signal of said one non-selected variable delay circuit is ahead of the phase of the output signal of said selected variable delay circuit by said specified phase difference and controls delay times of the other of non-selected two variable delay circuits so that the phase of the output signal of the other non-selected variable delay circuit is behind the phase of the output signal of said selected variable delay circuit by said specified phase difference and, based on the results of the comparison by said first phase comparator, controls a delay time of said selected variable delay circuit so that the phase of the output signal of said selected variable delay circuit is the same as the phase of said reference signal, and if said delay time of said selected variable delay circuit exceeds a variable time delay range of said selected variable delay circuit, controls said switching circuit so as to select another variable delay circuit.