| 摘要 |
PROBLEM TO BE SOLVED: To allow a feedback amplifier circuit to perform compensation by easily setting an operation point and appropriately canceling an offset voltage by an auto-zero operation. SOLUTION: A switch 7 in the feedback amplifier circuit performs an auto-zero operation by inputting an output signal from a switched operational amplifier 3 to an input terminal in an auto-zero operation period before an amplification period. A capacitor C2 stores and holds the offset voltage of an output terminal in the auto-zero operation period concerning the feedback circuit of the operational amplifier 3, and then, cancels the offset voltage of the input terminal through the use of the stored and held offset voltage in the amplification period. A switch 8b grounds the feedback point of the feedback circuit in the auto zero operation period. A capacitor C3 is inserted to the feedback point of the feedback circuit, stores and holds the offset voltage of the output terminal of the operational amplifier 3, in the auto zero operation period and then, cancels the offset voltage by the stored and held offset voltage together with the capacitor C2 in the amplification period. COPYRIGHT: (C)2008,JPO&INPIT
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