| 摘要 |
<p>The A/D converting circuit 20 is provided with a differential amplifying portion 21, a first variable capacitance portion 22A, a second variable capacitance portion 22B, a comparing portion 23, a connection controlling portion 24, a first feedback portion 25A and a second feedback portion 25B. Voltage values output as a differential signal from the first output terminal and the second output terminal of the differential amplifying portion 21 are converted to 6-bit digital values by a successive approximation type A/D converting circuit (made up of a first variable capacitance portion 22A, a second variable capacitance portion 22B, a comparing portion 23 and a connection controlling portion 24) and output. A difference in potential between the first common point P 1 and the second common point P 2 is fed back to the differential amplifying portion 21 by the first feedback portion 25A and the second feedback portion 25B, and again converted to a 6-bit digital value by the successive approximation type A/D converting circuit and output.</p> |
