| 摘要 |
PROBLEM TO BE SOLVED: To obtain a D/A converter circuit that conducts D/A conversion at a high speed with high precision. SOLUTION: The D/A converter circuit has an analog reference power supply 1, an output buffer 2, a multiplexer 3, a pre-buffer 4, and voltage changeover switches SW1-SW3. The pre-buffer 4 is operated at a power supply voltage different from the analog reference power supply 1 and outputs a voltage nearly equal to an output voltage of the analog reference power supply 1. An output voltage of the pre-buffer 4 is fed to the output buffer 2 within a prescribed period after a logic level of digital data is changed and an input parasitic capacitance of the output buffer 2 is charged/discharged. The output voltage of the analog reference power supply 1 is fed to the output buffer 2 after the prescribed period. Thus, charge/discharge current of the input parasitic capacitance is not supplied to the analog reference power supply 1 so as to suppress fluctuation in an output voltage of the analog reference power supply 1.
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