低电压低功耗伪差分两级运算跨导放大器设计

为了满足电池供电设备低功耗、低电压的要求,提出一种用于超低电压和低功率混合信号应用的、基于米勒补偿的两级全差分伪运算跨导放大器(OTA).该放大器电路使用标准的0.18μm数字CMOS工艺设计,利用PMOS晶体管的衬体偏置减小阈值电压,输入和输出级设计为AB类模式以增大电压摆幅.将输入级用作伪反相器增强了输入跨导,并采用正反馈技术来增强输出跨导,从而增大直流增益.在0.5 V电源电压以及5 pF负载下对放大器进行模拟仿真.仿真结果表明,当单位增益频率为35 kHz时,OTA的直流增益为88 d B,相位裕量为62°.与现有技术相比,所提出的OTA品质因数改善了单位增益频率和转换速率,此外,其功耗仅为0.08μW,低于其他文献所提到的OTA.

Design of low-voltage low-power pseudo-differential two-stage operational transconductance amplifier

In order to meet the low-voltage and low-power requirements of battery-powered equipment, a two-stage fully differential pseudo-operational transconductance amplifier(OTA)based on Miller compensation for ultra-low voltage and low-power mixed-signal application was proposed. A standard 0.18 μm digital CMOS process was used in the design of amplifier circuit, and the threshold voltage was reduced with the lining biasing of PMOS transistor. The input and output stages were designed as the class-AB mode to increase the voltage swing. The input transconductance was enhanced by using the input stage as the pseudo-inverter, and the output transconductance was improved with the positive feedback technology to increase the DC gain. The simulation for the OTA was performed at a supply voltage of 0.5 V with a load of 5 pF. The simulation results show that when the unity gain frequency is 35 kHz, the DC gain of OTA is 88 dB, and the phase margin is 62°. Compared with the existing technologies, the proposed OTA merit figure improves the unity gain frequency and slewing rate. Besides, the power consumption is only 0.08 μW, which is lower than that of OTA mentioned in other literatures.