| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a gradation selector circuit, having a low ON-resistance even near the middle potential, capable of preventing a leakage current and executing high-speed operations and operations having high precision output voltage. <P>SOLUTION: The gradation selector circuit which is to be used has a resistor string circuit 14 connected in series in between a higher side power supply and a lower side power supply, and a selector circuit 19 connected to the resistor string circuit 14 for selecting one value from among a plurality of analog voltages generated by the resistor string circuit 14, based on a control signal Φ/Φ- and outputting it to an output terminal. The selector circuit 19 comprises an analog switching circuit 11-1 for selecting an analog voltage near the middle. The analog switch circuit 11-1 comprises a P-type MOS transistor 22, having a source and a back gate electrodes to which the resistor string circuit 14 is connected, and a depletion N-type MOS transistor 23 having a source electrode, to which the drain electrode of the P-type MOS transistor 22 is connected and having a drain electrode, to which an output terminal is connected. <P>COPYRIGHT: (C)2004,JPO |
