低功耗恒定跨导轨对轨运算放大器设计技术研究

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

为了解决轨对轨运算放大器输入级跨导随共模输入电压变化的影响,采用实时共模电压监测技术,动态跟踪轨对轨运放输入级的跨导变化,通过对偏置电流的高精度定量补偿,从而实现了对输入级跨导的恒定性控制。基于0.18μm CMOS工艺进行了具体电路的设计实现,结果表明:在电源电压3.3 V、负载电阻100Ω、负载电容1 nF的条件下,运放增益为148 dB、相位裕度为61°、功耗为39.6μW,共模输入范围高达0~3.3 V,输入级跨导变化率仅为2.1%。

In order to solve the influence of the input-stage transconductance of the rail-to-rail operational amplifier(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 0.18 μm and CMOS process show that the op amp gain is 148 dB and the phase margin is 61° under the condition of power supply voltage 3.3 V,load resistance 100 Ω and load capacitance 1 nF. The total power consumption is only 39.6 microwatts,the common mode input range is as high as 0~3.3 V,and the transconductance change rate of the input stage is only 2.1%.