CLOCK GENERATOR AND SYSTEM INCLUDING SAME

摘要

A spectrum spread clock generator (SSCG)(100) includes: a digital control oscillator (DCO) (140) that generates an output clock with a frequency corresponding to an input code; and a phase comparison unit (120) that compares the output clock phase to a reference phase based on the input clock and a prescribed frequency multiplier (FCW), and outputs a phase difference signal (PHASE). A low pass filter (130) filters the phase difference signal and provides a DCO input code. The SSCG also includes: a waveform generator (150) that generates a prescribed spectrum spread wave; and a detection/correction unit (160) that detects the phase difference from the phase difference signal and corrects the DCO input code so as to reduce the phase difference. The spectrum spread wave is added to both the frequency multiplier and the DCO input code. An SSCG for which a comparatively high spread frequency can be set and which can achieve a desired spread rate is provided.