| 摘要 |
PROBLEM TO BE SOLVED: To perform A/D conversion of >=3 steps with high precision. SOLUTION: After a 2nd (2nd step) A/D conversion code n2 by an A/D converting circuit 1 is outputted, a switch S10 is turned off and a switch S11 is turned on to make an operational amplifier 3 and a capacitor CF operate as a hold circuit, thereby charging array capacitors C0 to C7 with the output voltage of the operational amplifier 3. Then switches S11 and S12 are turned off and S13 to S15 are turned on to initialize the electric charges of the capacitor CF to 0 and charge a capacitor CIN with (V1 plus the offset voltage of the operational amplifier 3). After S13 to S15 are turned off and S12 is turned on, the switch S10 is turned on and the switches S0 to S7 are switched to the side of a reference voltage terminal 2 or ground terminal GND according to a conversion code n2 to perform redistribution of electric charges.
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