JP2008219856A5 - - Google Patents

Claims (6)

A gradation generation circuit for generating a plurality of gradation voltages;
A gradation selector circuit having a plurality of analog switch circuits each for selecting one of the plurality of gradation voltages;
A semiconductor switch comprising a switch control circuit for controlling the operation of the gradation selector circuit,
Each of the plurality of analog switch circuits includes a MOS transistor having a source connected to a gradation voltage to be selected from the plurality of gradation voltages.
The switch control circuit includes:
A timing control circuit for supplying a gate voltage of the MOS transistor so as to control on / off of the MOS transistor;
And a back gate voltage control circuit for supplying a voltage substantially equal to the source voltage of the MOS transistor as a back gate voltage of the MOS transistor. The semiconductor switch according to claim 1,
The semiconductor switch according to claim 1, wherein the back gate voltage control circuit supplies, as a back gate voltage of the MOS transistor, a voltage that does not forward bias the PN junction between the source and back gate of the MOS transistor. The semiconductor switch according to claim 1,
The back gate voltage control circuit has the same internal configuration as the gradation generation circuit. The semiconductor switch according to claim 3, wherein
Each of the gradation generation circuit and the back gate voltage control circuit includes a resistor string circuit connected between an H-side power supply and an L-side power supply. The semiconductor switch according to claim 3, wherein
Each of the gradation generation circuit and the back gate voltage control circuit includes a current source, a resistor string circuit, and a diode connected in series between an H-side power source and an L-side power source. . A gradation generation circuit for generating a plurality of gradation voltages using a resistor element array;
A plurality of switch circuits each composed of a MOS transistor and receiving one gradation voltage from the gradation generation circuit as an input voltage;
The plurality of switch circuits using the same kind of resistor element array as the gradation generation circuit so as to reversely bias the PN junction between the source and back gate of each of the MOS transistors of each of the plurality of switch circuits. And a back gate voltage control circuit for supplying a voltage close to the source voltage of each of the MOS transistors as a back gate voltage of the MOS transistor.