Rail-to-Rail Operational Amplifiers

Abstract

The invention provides a rail-to-rail operational amplifier. Including: an input stage and an output stage, the input stage includes a first current source, a first input stage, a second current source, a second input stage, a third current source, a fourth current source and a folding stage, wherein: the first current source Generate a first constant current signal; the first input stage converts the first differential voltage signal into a first differential current signal and inputs it to the folding stage; the second current source generates a second constant current signal; the second input stage converts the first differential voltage signal The converted second differential current signal is input to the output stage; the third current source generates the third constant current signal; the fourth current source generates the fourth constant current signal; the folding stage inputs the first differential current signal to the output stage. In the rail-to-rail operational amplifier provided by the present invention, the input stage is asymmetric, so that the common mode voltage output by the input stage is not Vdd / 2, and the driving voltage of the output stage is relatively large, so that the bandwidth of the signal output by the output stage is relatively large.

Description

technical field [0001] The invention relates to the technical field of power electronics, in particular to a rail-to-rail operational amplifier. Background technique [0002] At present, with the gradual reduction of the feature size of the integrated circuit process, the size of the chip becomes smaller and smaller, and the voltage Vdd of the power supply in the chip is also gradually reduced. [0003] In the prior art, the input stage of a traditional rail-to-rail operational amplifier has a symmetrical structure, and the common-mode voltage output by the input stage is Vdd / 2. figure 1 circuit diagram for existing rail-to-rail operational amplifiers, such as figure 1 As shown, it includes an input stage 100 and an output stage 200, wherein in the input stage: the first field effect transistor 1 and the second field effect transistor 2 are N-type metal oxide semiconductor (N-Mental-Oxide-Semiconductor, NMOS for short) input For the tube, the current source including the t...

AI Technical Summary

Problems solved by technology

[0005] The present invention provides a rail-to-rail operational amplifier, which is used to solve the problem in the prior art that when the power supply voltage Vdd is small, the bandwidth of the signal output by the output stage is small

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