AUTO-ZERO CIRCUIT OF OPERATIONAL AMPLIFIER

摘要

An auto-zero circuit of an operational amplifier is disclosed, and the auto-zero circuit has: a micro-control unit and a digital potentiometer; the micro-control unit is used to obtain a voltage value of an offset voltage of the output end when there is no input in the operational amplifier, and generates a control signal which causes the voltage value of the offset voltage to be smaller than a first threshold value according to the voltage value of the offset voltage; the digital potentiometer is used to adjust a resistance thereof according to the control signal.

主权项

1. An auto-zero circuit of an operational amplifier, comprising:
an operational amplifier including an input end, an output end and an auto-zero end, wherein the input end receives a input signal; the output end processes the input signal to generate an output signal; and the auto-zero end executes an auto-zero operation for the operational amplifier; an analog-to-digital converter converting the output signal to a digital signal; a micro-control unit obtaining a voltage value of an offset voltage of the output end according to the digital signal when there are no input signals in the input end, wherein the micro-control unit compares an amplitude of the offset voltage to a first threshold value so as to generate a comparison result and generate a control signal according to the comparison result, wherein the control signal causes the voltage value of the offset voltage to be smaller than the first threshold value; a digital potentiometer adjusting a resistance thereof according to the control signal, in order to execute the auto-zero operation for the operational amplifier; and a temperature sensing module detecting a current environment temperature and recording an initial temperature after finishing the previous auto-zero operation.