Semiconductor Components Industries, LLC

Sanyo Semiconductor Co., Ltd.

Tsuyoshi Yoshimura

Taichiro Kawai

The invention provides a level shift circuit that prevents an offset when the supply voltage changes. A level shift circuit has a differential amplification circuit, a current generation circuit, a capacitor and a holding circuit. An input signal from the optical pickup is inputted to the non-inversion input terminal of the differential amplification circuit. First, by turning on a first switch, a feedback loop is formed by the differential amplification circuit, the current generation circuit and the capacitor to perform a level shift, and the voltage charged in the capacitor is held by the holding circuit. Then by turning off the first switch and turning on a second switch, the voltage held by the holding circuit is applied to the non-inversion input terminal of the differential amplification circuit to perform a level shift.

Level shift circuit

The invention provides a charge pump circuit which reduces rise time of an output current even when an input signal is of high frequency. PMOSand PMOShave gates connected to each other, and the gate of the PMOSis connected to the drain thereof. A supply potential (Vdd) is applied to the sources of the PMOSand the PMOS, and the PMOSand the PMOSform a current mirror circuit. First and second switching elements and a first constant-current source are connected to the drain of the PMOS. A connection point (a node) of the first switching element and the second switching element is connected to an output terminal. The drain of the PMOSis connected to the first constant-current source through a third switching element, and connected to a second constant-current source through a fourth switching element.

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Sumoto, Japan

Tsuyoshi Yoshimura