一种低失调高压大电流集成运算放大器

High Voltage and High Current Integrated Operational Amplifier with Low Offset Voltage and Current

基于结型场效应晶体管(JFET)和双极型晶体管(BJT)兼容工艺,设计了一种低失调高压大电流集成运算放大器。电路输入级采用p沟道JFET (p-JFET)差分对共源共栅结构;中间级以BJT作为放大管,采用复合有源负载结构;输出级采用复合npn达林顿管阵列,与常规推挽输出结构相比,在输出相同电流的情况下,节省了大量芯片面积。基于Cadence Spectre软件对该运算放大器电路进行了仿真分析和优化设计,在±35 V电源供电下,最小负载电阻为6Ω时的电压增益为95 dB,输入失调电压为0.224 5 mV,输入偏置电流为31.34 pA,输入失调电流为3.3 pA,单位增益带宽为9.6 MHz,具有输出9 A峰值大电流能力。

A high voltage and high current operational power amplifier (HV-HC-OPA)with low offset voltage and current was proposed and verified based on junction field-effect-transistor (JFET)and bipolar junction transistor (BJT)compatible process.The input stage of the HV-HC-OPA is implemented by a p-JFET differential pair cascode structure.The middle stage uses BJTs as amplifiers and a compound active load structure is adopted.The output stage is composed of compound npn Darlington structure which can save a lot of chip area under the same output current compared to the traditional push-pull stage.The circuit was simulated and optimized based on Cadence Spectre simulator.Simulation results show that 95dB voltage gain on 6Ω load,0.2245 mV input offset voltage,31.34 pA input bias current,3.3 pA input offset current and 9.6 MHz unity gain-bandwidth under ±35V double supply voltages.The maximum output peak current can reach 9 A.