Low power voltage transconductance adjustable transconductance-constant rail-to-rail input operational amplifier

Abstract

The invention relates to a low-power voltage transconductance adjustable transconductance-constant rail-to-rail input operational amplifier, which comprises a transconductance-constant control circuit, a rail-to-rail input stage and an output stage, wherein the transconductance-constant control circuit makes the transconductance of the rail-to-rail input operational amplifier approximate to twice a reciprocal of a resistance value of a reference resistor by feeding back and controlling the tail current of the rail-to-rail input stage. Simultaneously, the transconductance of the rail-to-rail input operational amplifier can be changed by changing the resistance value of the reference resistor. The rail-to-rail input operational amplifier can work under a low power voltage, and has the advantages of rail-to-rail common mode input range, transconductance adjustability, constant transconductance and the like.

Description

technical field [0001] The invention relates to the technical field of operational amplifiers, in particular to a rail-to-rail input operational amplifier with low power supply voltage and constant transconductance. Background technique [0002] An operational amplifier is an important building block in an analog integrated circuit. With the rapid development of microelectronics manufacturing process technology, the feature size of devices is getting smaller and smaller, and the power supply voltage they can withstand is getting lower and lower, which will limit the performance of operational amplifiers, such as the common-mode input range of operational amplifiers. When an op amp is used as a buffer, it needs a common-mode input range as large as the input signal range. This requires the use of rail-to-rail input op amps for large dynamic range. [0003] A rail-to-rail input op amp is a special type of amplifier whose common-mode input voltage ranges from the negative sup...

AI Technical Summary

Problems solved by technology

However, in the existing circuit implementation methods, since the NMOS differential input pair of the input stage and the replicated NMOS differential input pair have different common-mode input voltages (the former is a rail-to-rail common-mode input voltage, while the latter is a fixed common-mode input voltage), which makes the transconductance of the two have a large difference when the common-mode input voltage is low, and it is also required to work at a higher power supply voltage, otherwise it will cause transconductance across the entire common-mode input range The conductance has relatively large fluctuations (for example, at a working power supply voltage of 3V, its transconductance fluctuation is about 3-4%, while at 1V, its transconductance fluctuation is about 11%)

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