Research on Low Power Constant Transconductance Rail-to-Rail Operational Amplifier Technology

In order to solve the influence of the input stage transconductance of the rail-to-rail op amp with the common-mode input voltage change, real-time common-mode voltage monitoring technology is used to dynamically track the transconductance change of the rail- to- rail op amp input stage through the bias current. High-precision quantitative compensation for constant control of the input stage transconductance. The design and implementation of the specific circuit based on 0.18μm and CMOS process show that the op amp gain is 148dB and the phase margin is 61° under the condition of power supply voltage 3.3V, load resistance 100Ω and load capacitance 1nF. The total power consumption is only 39.6 microwatts, the common mode input range is as high as 0-3.3V, and the transconductance change rate of the input stage is only 2.1 %.