High-precision operational amplifier circuit integrating chopping and automatic zero setting technologies

Abstract

The invention relates to the technical field of integrated circuits. The invention discloses a high-precision operational amplifier circuit integrating chopping and automatic zero setting technologies. The operational amplifier circuit comprises a main operational amplifier unit, an input low-pass filter unit, a first-stage chopping unit, a direct-current mismatch operational amplifier unit, a second-stage chopping unit and a chopping low-pass filter unit, the chopping noise reduction technology and the automatic zero setting technology are integrated in one chip, input noise can be effectively eliminated, the direct-current offset voltage error of the operational amplifier can be effectively reduced, and therefore the precision of the operational amplifier circuit is improved. The circuitis applied to a closed-loop negative feedback operational amplification system with high-precision output. Direct current mismatch is amplified into a main operational amplifier loop, amplification is carried out again through the main operational amplifier loop, a high-gain mismatch error is obtained, positive input and negative input are automatically adjusted through an operational amplifier by means of negative feedback in an application system, the positive input and the negative input are made to be further close to a virtual short state, and then the precision of an operational amplifier circuit is improved. High-frequency noise is filtered by adopting input low-pass filtering, and noise can be further reduced by adopting a chopping method.

Description

technical field [0001] The invention relates to the technical field of electronic circuits, in particular to a high-precision operational amplifier circuit integrating chopping and automatic zero adjustment, which can be used in a closed-loop feedback operational amplifier system requiring high-precision output. Background technique [0002] High-precision operational amplifiers are a type of operational amplifiers that are less affected by temperature, that is, small temperature drift, low noise, and high sensitivity, and are suitable for small signal amplification. With the rapid development of the high-tech industry, high-precision operational amplifier circuits, as a kind of operational amplifiers, are more and more widely used. High-precision operational amplifiers have a wide range of applications, and can be used in measuring instruments, control systems, HAVC, program control, etc. in the industrial field. In the medical field, there are also ultrasound, gas analysi...

AI Technical Summary

Problems solved by technology

[0003] In a high-precision operational amplifier circuit, in order to reduce the offset and noise interference of the operational amplifier, the traditional chopper amplifier generally adopts an automatic zeroing method, which requires an additional zeroing or offset storage circuit, and its accuracy and temperature characteristics are limited; or use The multi-stage composite amplifier structure of the chopper-stabilized method, which combines DC stability and good temperature characteristics, but produces high-frequency switching "noise" signals, which limits the available signal bandwidth

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