| 摘要 |
PROBLEM TO BE SOLVED: To solve the problem that S/N deteriorates because switching noise can not be sufficiently eliminated in an amplifier circuit using a chopper amplifier. SOLUTION: An averaging circuit 24 is provided at an output of the chopper amplifier 22. The averaging circuit 24 samples output voltage V<SB>C</SB>(t) of the chopper amplifier 22 at a plurality of sampling times t<SB>i</SB>and generates and outputs average voltage about the output voltage V<SB>C</SB>(t) at each sampling time. To eliminate switching noise, the time t<SB>i</SB>is set to a time within the interval of switching operations of the chopper amplifier 22. Further, to eliminate high-pitched noise of thermal noise or the like, sampling is performed in a frequency higher than the switching operation. COPYRIGHT: (C)2008,JPO&INPIT
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