DIFFERENTIAL AMPLIFYING CIRCUIT AND MICROPHONE/AMPLIFIER SYSTEM

摘要

The differential amplifying circuit includes a first bias resistor having a variable resistance and connected between the first input terminal and the reference voltage node. The differential amplifying circuit includes a second bias resistor having a variable resistance and connected between the second input terminal and the reference voltage node. The differential amplifying circuit includes a controlling circuit that controls the resistance of the first bias resistor and the resistance of the second bias resistor in synchronization with each other.

主权项

1. A differential amplifying circuit that amplifies signals input to a first input terminal and a second input terminal and outputs amplified signals, the differential amplifying circuit comprises:
a first input resistor connected to the first input terminal at a first end thereof; a second input resistor connected to the second input terminal at a first end thereof; an operational amplifier that is connected to a second end of the first input resistor at a non-inverting input terminal thereof and to a second end of the second input resistor at an inverting input terminal thereof and outputs a first differential signal at an inverting output terminal thereof and a second differential signal at a non-inverting output terminal thereof; a first feedback resistor connected between the inverting output terminal and the non-inverting input terminal of the operational amplifier; a second feedback resistor connected between the non-inverting output terminal and the inverting input terminal of the operational amplifier; a first bias resistor having a variable resistance and connected between the first input terminal and a reference voltage node; and a second bias resistor having a variable resistance and connected between the second input terminal and the reference voltage node.