Abstract: A clock extraction circuit includes an edge detection unit for detecting a phase at which a trailing edge or a leading edge of input data is coincided with each other, and a phase judgement unit for comparing an edge position of the detected input data and a position of an input clock and for putting a weight, wherein the weight is put so that a shifting amount of the input clock is varied depending on a difference between the edge position of the input data and the position of the input clock.

Abstract: It is an object to realize a synchronization circuit with small size and low consumption power which enables capturing and phasing of external data without running external clock in parallel. Internal clock (2) is delayed by a delay line (1) to produce delay clocks (3), and one of the delay clocks (3) having its rise almost corresponding to that of an external data signal (6) becomes a select clock (5). An elastic store circuit (7) is a circuit which controls a row of D-latches with a row of C elements. Thus the elastic store circuit (7) captures the external data signal (6) with enough set up hold time at timing of the select clock (5) and then outputs the captured external data as an internal data signal (8) in synchronization with the internal clock (2).