Fujitsu Corporation

Tomonobu Miyata

Koji Okada

Takaaki Ido

This invention provides a clock generator which is capable of improving modulation accuracy without accompanying an increase in consumption current by steady current when spectrum spread of a clock signal is executed. The phase balanced voltage Vf to be inputted to the voltage control oscillator (VCO)is modulated within a dead band region in which no difference signals Pr, Pr are outputted from the charge pump circuitwhen a difference in oscillation frequency between an output clock signal fo and a reference clock signal fr is detected. Consequently, the output clock signal fo is changed within the range of a lock frequency in a PLL circuit, so as to execute the spectrum spread of the output clock signal fo while maintaining the lock state of the oscillation frequency in the PLL circuit.

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Kasugai, Japan

Tomonobu Miyata