低压恒跨导增益提高CMOS运算放大器的设计

Design of CMOS Operational Amplifier with Low Voltage Constant Transconductance and Gain Boosting

设计和研究了一种低压恒跨导增益提高互补金属氧化物半导体(CMOS)运算放大器。输入级采用互补差分对结构,使共模输入电压范围达到轨到轨,通过3倍电流镜控制尾电流使输入级总跨导恒定。中间级为增益提高级,通过反馈增大输出阻抗提高增益。输出级采用AB类结构,通过米勒补偿控制零点使系统稳定,此运放可用于低压低功耗电子设备中。整个电路用CSMC 0.5μm BCDMOS工艺参数进行设计,工作电压为2.7 V。Spectre仿真结果显示,此运放实现了直流开环增益90 dB(负载电阻R L=600Ω),相位裕度70°,增益带宽积1.4 MHz,静态电流0.18 mA。设计的运算放大器满足设计指标。

A complementary metal-oxide-semiconductor （CMOS） operational amplifier with low voltage constant transconductance and gain boosting was designed and studied. The input stage used complementary differential pairs to make the common-mode input voltage rail-to-rail. The tail-current was controlled by three times current mirror to keep the input stage transconductance constant. The intermediate stage was gain boosting stage, which increased the output impedance through feedback to boost the gain. The output stage used class AB structure, Miller compensation made the system stable by controlling the zero. The operational amplifier can be used for low voltage low power electronic devices. The central semiconductor manufacturing corporation （CSMO） 0. 5 μm BCDMOS process was adopted to achieve the circuit, the single power supply voltage is 2. 7 V. Spectre simulation results show that DC open-loop gain is 90 dB （the load resistance RL is 600Ω）, the phase margin is 70°, the gain bandwidth product is 1.4 MHz, the quiescent current is 0. 18 mA. The designed operational amplifier meets the design specifications.