Hitachi, Ltd.

Hitachi Video and Information System, Inc.

Tsuyoshi Tateyama

Akira Uragami

Eisaku Saiki

Shintaro Suzumura

Fukashi Ohi

A phase locked loop IC comprising a voltage controlled oscillator which generates a clock signal in accordance with a control voltage, a first ECL input buffer which is an input buffer for a signal to be synchronized, a phase-lock capture circuit for producing a current determinative of the control voltage in accordance with the phase difference and the frequency difference between the signal to be synchronized and the clock signal, and a phase-lock follow-up circuit for producing a current determinative of the control voltage in accordance with the phase difference between the clock signal and the signal to be synchronized; wherein the supply voltage system of the first ECL input buffer is so disposed as to be isolated from any of the supply voltage systems of the voltage-controlled oscillator, the phase-lock capture circuit and the phase lock follow-up circuit, while the ground system of the first ECL input buffer is so disposed as to be insolated from any of the ground systems of the voltage-controlled oscillator, the phase-lock capture circuit and the phase-lock follow-up circuit.

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Yokohama, Japan

Tsuyoshi Tateyama