Nec Corporation

Ricoh Company, Ltd.

Masazumi Sukekawa

Mitsutaka Iwasaki

Toshihiro Tsukagoshi

Michihito Ootsuki

A PLL control circuit, which outputs a PLL clock in response to a reference clock, is provided with a frequency adjustment circuit which performs frequency adjustment such that the PLL clock frequency is substantially constant even when the reference clock varies. The frequency adjustment circuit changes a set value in a counter, which determines the PLL clock frequency, in accordance with the variation in the reference clock frequency.

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Saitama, Japan

Masazumi Sukekawa