Clock generating circuit and clock generating method

摘要

The invention provides a clock generating circuit for generating a spectrum spread clock and carrying out highspeed and accurate phase control of a reference clock signal and an output clock signal, which is composed of compact circuits, and a method for generating the clock. The spectrum spread clock generating circuit (1) is provided with a phase comparator unit (10) that compares the reference clock signal (CLKS) with the internal clock signal in terms of a phase difference, and outputs a control current (ICI) in compliance with the result of comparison; a clock generating unit (20) for generating an output clock signal (CLKO); a phase difference signal modulating unit (30) for outputting a control current (IC3); and a delay unit (40) for delaying the output clock in compliance with the control current (IC3) and outputting the internal clock signal (CLKN).