新型低压微功耗伪差分跨导放大器设计

A Novel Low-voltage Micro-power Pseudo-differential CMOS OTA

本文针对全差分跨导放大器电源电压偏高、功耗较大,以及常规伪差分跨导放大器增益和共模抑制比不高的问题,采用带反相器和共模前馈的伪差分输入级、自偏置电流镜结构的输出级,以及正体偏置技术和TSMC 40nm CMOS工艺,设计一个新型低压微功耗高增益高共模抑制比的伪差分跨导放大器。Cadence Spectre仿真结果表明,在0.5V的电源电压下,该跨导放大器的开环增益为51.8dB,单位增益带宽为18.6 MHz,相位裕度为70°,共模抑制比达到135dB,电源抑制比达到107dB,而功耗仅为3μW,具有较好的综合性能,可作为大多数要求较高的前端微弱信号放大器。

In this paper, a novel pseudo-differential transconductance amplifier with low-voltage micro- power high-gain high common-mode rejection ratio is designed, aimed at the problems of high power supply voltage, high power consumption in the full-differential transconductance amplifier, as well as small gain and low common mode rejection ratio in the conventional pseudo-differential transconductance amplifier. The proposed transeonductance amplifier is composed of two stages. The first stage is a pseudo-differential input structure with inverter and common mode feedforward. The second stage is a self-bias current mirror output structure. The positive body bias technique and the TSMC 40nm CMOS process are adopted. Cadence Specter simulation results show that under the power supply voltage of 0.5 V,the transconductanee amplifier open-loop gain is 51.8 dB, the unit gain bandwidth is 18.6 MHz, the phase margin is 70°,the common mode rejection ratio is 135dB, and the power supply rejection ratio is 107 dB,while the power consumption is only 3 μW. This amplifier has good comprehensive performance and can be used for most front-end weak signal amplifiers with higher demanding.