Patent Number: 6,486,716

Title: Phase compensation circuit

Abstract: The invention provides a phase compensation circuit that can carry out phase compensation grater than the variable delay time range of a variable delay circuit without increasing more than necessary the delay time of the variable delay circuit even in the case that the phase of the reference signal and the phase of the feedback signal change because of changes in the operating environment due to fluctuations in the power source voltage and fluctuations in temperature. The phase compensation circuit that compensates the phase of a clock signal provides a plurality of variable delay circuits, a first phase comparator that compares the phase of a reference signal to the phase of a feedback signal, a second phase comparator that compares the phases of the plurality of variable delay circuits, a switching circuit that switches the outputs of the plurality of variable delay circuits, and a control circuit. First, one among the plurality of variable delay circuits is selected as the path from the input to the output, then the output of the other variable delay circuits is controlled so as to differ from the phase of the output of the selected variable delay circuit by one cycle, and when the maximum value or minimum value of the variable delay time range of the selected variable delay circuit is reached, the output of the other variable delay circuits is switched from the path from the input to the path of the output.

Inventors: Minami; Koichiro (Tokyo, JP), Mizuno; Masayuki (Tokyo, JP)

Assignee: NEC Corporation

International Classification: H03L 7/087 (20060101); H03L 7/081 (20060101); H03L 7/08 (20060101); H03L 007/00 ()

Expiration Date: 11/26/2019