| 摘要 |
PROBLEM TO BE SOLVED: To reduce the offset of a comparator and to improve conversion precision in A/D conversion by uniformizing error factors acting on each input to a comparator having an offset cancel function. SOLUTION: An analog switch SW11 which is electrically short-circuited is provided between the differential input terminals of a differential stage 8 connected to hold capacitors C3 and C4 and differential voltage is prevented from generating between the input terminals of an offset cancel comparator 10 when sampling is completed. The switch SW11 that short-circuits each input of the first stage of a differential amplifier circuit is provided and the switch SW11 is made into a conductive state in the initial state in the same manner as the other analog switches and is made into an off state at the final an offset cancel operation. Thus, a component working as an error factor only on the capacitor C4 is also added to the capacitor C3 intentionally to uniformize and make potential difference between differential input terminals zero.
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