A self-zero operational amplifier

Abstract

A self-zero operational amplifier belongs to the technical field of analog integrated circuits. The amplifier comprises an operation amplification module and a self-zero adjusting module, wherein theoperation amplification module comprises a pair of differential input pairs of tubes, the grids of the differential input pairs of tubes are used as the positive input terminal and the negative inputterminal of the self-zero adjusting operational amplifier respectively, and the output terminal of the operation amplification module is used as the output terminal of the self-zero adjusting operational amplifier; the self-zero module controls the output signal of the self-zero operational amplifier by controlling the on and off of each switch, the common mode signal and the power supply voltageare connected into the self-zero module, and the self-zero function is realized by using the charge and discharge of the capacitor, which improves the precision of the operational amplifier. In some embodiments, the stability of the op amp is ensured using dynamic capacitance compensation adjustment by adding an enable block to reduce the power consumption of the op amp. The self-zeroing operational amplifier proposed in this paper can be used in programmable gain operational amplifier to realize its own offset calibration.

Description

technical field [0001] The invention belongs to the technical field of analog integrated circuits, and in particular relates to a self-adjusting operational amplifier, which can be used to form a programmable gain operational amplifier (PGA) by combining with a resistance switch array. Background technique [0002] As the entrance of information technology, sensors play an important role in the acquisition and conversion of information. Normally, a sensor converts physical quantities containing a variety of information into electrical signals such as voltage and current signals that can be recognized and processed by circuits, and these electrical signals are generally continuously changing analog signals, so large-scale digital logic operation units It cannot be directly acquired and processed, and an analog-to-digital converter (ADC) is required to convert continuous analog signals into discrete digital signals. However, due to the accuracy of the sensor and the rapid cha...

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Problems solved by technology

First, the programmable gain operational amplifier will affect the output load of the sensor, resulting in changes in the output signal of the sensor, especially for resistive pressure sensors; secondly, the programmable gain operational amplifier will amplify the electrical signal, and the self-generated Noise and offset will also participate in the amplification, causing the signal sampled by the ADC to include both the amplified sensor signal and the amplified noise and offset voltage. Therefore, the programmable gain operational amplifier itself is required to perform offset calibration

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