Oki Semiconductor Co., Ltd.

Lapis Semiconductor Co., Ltd.

Koji Yamazaki

Atsushi Hirama

Koji Higuchi

Hideaki Hasegawa

Hiroyoshi Ichikura

Takeki Ebina

A display driver includes a gamma correction data transmission unit that transmits a plurality of gamma correction data pieces one by one in each predetermined period. A brightness level indicated by a video signal is converted into a gradation voltage with a gamma characteristic based on the gamma correction data piece transmitted from the gamma correction data transmission unit.

Display driver and semiconductor device

An offset-reducing output circuit of a source driver adapted to drive a liquid crystal device. The output circuit includes an operational amplifier having a non-inverting input to receive a reference voltage. The output circuit also includes input and output capacitors. One terminal of the input capacitor and one terminal of the output capacitor are connected to a node extending to an inverting input of the operational amplifier in at least a normal output operation mode. The output circuit also includes a switching circuit to short both terminals of the input capacitor and both terminals of the output capacitor in a reset operation so that the reference voltage is applied to the terminals of the input and output capacitors respectively. The switching device applies a gray scale voltage to an opposite terminal of the input capacitor in a normal operation mode.

Output circuit for reducing offset for use in source driver adapted to drive liquid crystal device

A multi-input operational amplifier circuit operable with a high degree of accuracy and in a small area, a D/A converter using the multi-input operational amplifier circuit, and a drive circuit or driver for a display device, using the D/A converter. In embodiments of the multi-input operational amplifier circuit, a constant current source of a third differential amplifier circuit that causes a doubled constant current i&#xd7;2 to flow with respect to constant current sources of first and second differential amplifier circuits by application of two types of bias voltages thereto is configured using PMOS of the same number and size. Therefore, operations equivalent to those of a conventional circuit may be realized by the three constant current source PMOSs, and a smaller chip size may be required.

Multi-input operational amplifier circuit, digital/analog converter using same, and driver for display device using same

The present invention provides a load capacity driving circuit that is inexpensive and has a high driving capability. When an input signal changes to low potential, gate voltage of an output stage of an amplifying circuit increases, an NMOS transistor MNO turns on, and an NMOS transistor MNincreases potential of a node NGAT. Due thereto, an NMOS transistor MNOalso turns on, and a load capacity is discharged via the NMOS transistor MNO and the NMOS transistor MNO. Further, when the input signal changes to high potential, gate voltage of the output stage of the amplifying circuit decreases, a PMOS transistor MPO turns on, and a PMOS transistor MPdecreases potential of a node PGAT. Due thereto, a PMOS transistor MPOalso turns on, and the load capacity is charged from a constant voltage source via the PMOS transistor MPO and the PMOS transistor MPO

Load capacity driving circuit

The present invention provides a drive circuit suitable for use in a liquid crystal display, comprising an op amp which has an inversion input, a non-inversion input and a first output and of which the inversion input and the first output are connected to each other; a first PMOS transistor having a gate to which a node for the non-inversion input of the op amp is connected, and a source to which a node for the output of the op amp is connected; a first NMOS transistor having a gate to which a drain of the first PMOS transistor is connected, a drain to which the node for the output of the op amp is connected, and a source connected to ground; and a second NMOS transistor having a gate supplied with a predetermined first voltage, a drain to which the drain of the first PMOS transistor is connected, and a source connected to ground.

Drive circuit and drive device for liquid crystal display

An operational amplifier includes a differential amplifier connected between an input and an output port of the operational amplifier, a phase compensator capacitance connected between the differential amplifier and the output port, a switching transistor for controlling the connection between the phase compensator capacitance and the differential amplifier, a detection transistor responsive to a potential difference between the input and output ports to be rendered conductive, and a control transistor responsive to the detection transistor for controlling the switching transistor. The operational amplifier has its slew rate improved without detracting from stability against oscillation and continuity of the output waveform.

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Ibaraki, Japan

Koji Yamazaki