Patent ID: 7482963

Claim:
A D/A conversion circuit which comprises a reference voltage generating circuit which generates respectively a plurality of analog voltages for D/A conversion at a plurality of terminals, which connects the respective analog voltages of the reference voltage generating circuit respectively to a predetermined output via a plurality of switch circuits and which obtains one of the plurality of analog voltages at the predetermined output as an analog conversion voltage by selectively turning ON/OFF of the plurality of switch circuits in response to data, wherein in the D/A conversion circuit a unit region serving as a circuit element is formed in an IC by providing respectively contact pads at both ends in a rectangular guard ring region and at the center thereof and by arranging and forming a plurality of MOS switch transistors respectively between these contact pads, the contact pads at both ends in the unit region respectively receive one of the plurality of analog voltages, the contact pad at the center is connected to the predetermined output, the respective switch transistors in the unit region are respectively operated as the switch circuits, thereby, by selecting ON/OFF of the plurality of switch transistors in the unit region in response to the data the analog conversion voltage is obtained.