| 摘要 |
PROBLEM TO BE SOLVED: To provide an offset cancellation device capable of canceling offset even when a capacitive or resistance device is connected to the outside of an operational amplifier, and of outputting a signal during the canceling operation of offset. SOLUTION: This offset cancellation device is configured to run with the combination of output signals fewer in number than output signals to be output from a plurality of output circuits 16, each of which adjusts the gain of an input signal supplied to an operational amplifier 210. A selection output circuit 20 selects and outputs the prescribed number of output signals of a plurality of output circuits 16 necessary for driving the device. A judgement circuit 30 compares an output signal which has not been selected with a reference signal to adjust the gain of the output circuit 16, and cancels the offset of the operational amplifier 210. In the operation amplifier 210, a plurality of CAP groups are configured by combining feedback capacitors 226 by different number of aggregates, and whether or not those feedback capacitors function for each CAP group is switched until the judgement of normality is made by the judgement circuit 30. COPYRIGHT: (C)2009,JPO&INPIT
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