| 摘要 |
PROBLEM TO BE SOLVED: To provide a highly accurate amplifier circuit capable of reducing offset voltage and setting gain over a wide range from low gain up to high gain and to provide a magnetic sensor. SOLUTION: The amplifier circuit includes: a first amplifier 10 for respectively amplifying a first input signal Vi1 and a second input signal Vi2 and outputting the amplified signals as a first signal and a second signal; a second amplifier 20 for differentially amplifying a third signal input to a first input terminal and a fourth signal input to a second input terminal in respect to reference potential and outputting a first output signal from an output terminal; a first capacitor C1 whose one end is connected to the first amplifier 10 to input the first signal; a second capacitor C2 whose one end is connected to the first amplifier 10 to input the second signal and the other end is connected to the second input terminal to output the fourth signal; and a first switch circuit 41 capable of varying connection states between the output terminal and the other end of the first capacitor C1 and among the first input terminal, the second input terminal and the reference potential. COPYRIGHT: (C)2011,JPO&INPIT
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