| 摘要 |
PURPOSE:To increase the permissible error range of the resistance in use, by providing an electronic switch at a resistance for earth at the part where the lowest significant digit bit is formed and controlling the electronic switch with the counter pulse. CONSTITUTION:A terminal B00 of a switch control logical circuit is connected to the S00-th electronic switch controlling terminal. The other end of the electronic switch S00 is connected to a reference voltage input terminal 1 with another end earthed. When the switch S00 is earthed with a switch S01 set in a reference voltage supply mode, the voltage of a terminal P2 is set at 1/3.VREF. In the same way, the voltage of the terminal P2 is set at 1/3.VREF also in the contrary case. Then the voltage is set at 2/3.VREF when the reference voltage is applied to both switches S00 and S01. As a result, an error of voltage variation degree caused when being switched to an electronic switch on a bit can be suppressed by operating the bit having the minimum degree of variation. |
