Patent ID: 7961042

Claim:
An amplifier circuit, comprising: a first amplifier amplifying a first and a second input signal, and outputting a first and a second signal; a second amplifier amplifying a difference between a third signal of a first input terminal and a fourth signal of a second input terminal, and outputting a first output signal from an output terminal; a first capacitor, having one terminal connected to the first amplifier, receiving the first signal; a second capacitor, having one terminal connected to the first amplifier, and another terminal connected to the second input terminal, receiving the second signal and outputting the fourth signal; and a first switch circuit, switching a connection of the output terminal, another terminal of the first capacitor, the first input terminal, and the second input terminal, and switching to supply the second input terminal and the another terminal of the first capacitor with a reference potential, the first switch circuit configured to be a first state, wherein the first switch circuit connects the first input terminal to the second input terminal, and the output terminal to the another terminal of the first capacitor to supply a potential of the another terminal of the first capacitor with a potential of the first output signal output by the second amplifier set to a gain of unity, supplies the second input terminal and the another terminal of the second capacitor with the reference potential, and the first capacitor and the second capacitor are charged, and a second state, wherein the first switch circuit connects the first input terminal to the another terminal of the first capacitor, provides the output terminal and the second input terminal in an open state, and the second amplifier amplifies a difference between a signal of the another terminal of the first capacitor and a signal of the another terminal of the second capacitor to output the first output signal.