Patent ID: 8374363
Filing Date: 2013-02-12
Classification: H01L,H03F,H04R

Abstract:
1. An amplifier circuit of a capacitor microphone, comprising: a capacitor microphone generating an input signal corresponding to a sound received by the capacitor microphone; an operational amplifier comprising an input terminal and an output terminal, the input signal from the capacitor microphone being applied to the input terminal; a first feedback capacitor connected between the output terminal and the input terminal of the operational amplifier and configured to increase a capacitance in response to an increase in an amplitude of the input signal; and a feedback resistor connected between the output terminal and the input terminal of the operational amplifier, wherein the first feedback capacitor comprises a first MOS transistor comprising a first gate, a first back gate, a first source and a first drain and a second MOS transistor comprising a second gate, a second back gate, a second source and a second drain, the first gate is connected to the second back gate, and the second gate is connected to the first back gate.