一种针对小信号探测的低噪声放大器  

A Low Noise Amplifier for Small Signal Detection

作　　者：马伟 王宇 王美玉 肖知明 胡伟波 Ma Wei;Wang Yu;Wang Meiyu;Xiao Zhiming;Hu Weibo(College of Electronic Information and Optical Engineering,Nankai University,Tianjin 300350,China)

机构地区：[1]南开大学电子信息与光学工程学院,天津300350

出　　处：《半导体技术》2022年第9期712-718,共7页Semiconductor Technology

基　　金：深圳市科技创新委员会资助项目(JCYJ20180508161601937)。

摘　　要：针对放大器中的直流偏移和低频噪声干扰问题,设计了一种具有4种工作状态的低噪声放大器。该放大器综合利用了斩波技术和自归零技术,通过对噪声进行调制和采样,实现了对以1/f噪声为代表的低频噪声和以失调电压为代表的直流偏移的抑制。鉴于自归零技术是一种离散时间采样技术,该放大器还采用了乒乓结构,通过4种电路状态的交替工作,实现了放大器的连续稳定输出。该放大器芯片基于0.5μm CMOS工艺设计制备,片上面积约1 mm^(2),供电电压(V_(DD))为3~5.5 V,输入共模电压范围为+0.2 V至V_(DD)-0.2 V。测试结果表明,该放大器的电源抑制比为62 dB,共模抑制比为112 dB。在4 V供电电压和室温条件下,放大器的残余失调电压为4.2μV,在1~400 Hz带宽内的有效输入参考噪声为5.81μV。Aiming at reducing DC offsets and low-frequency noise in amplifiers,a four-state low-noise amplifier was designed based on chopping technology and auto-zero technology.Through modulating and sampling the noise,the proposed amplifier achieves a good suppression of the low-frequency noise represented by 1/f noise and DC interference represented by offset voltages.Considering the auto-zero technology is a discrete-time sampling technique,the proposed amplifier adopts a ping-pong architecture.With four circuit states working alternately,it can output continuously and steadily.The amplifier chip was designed and manufactured based on 0.5μm CMOS process with an on-chip area of around 1 mm^(2).The power supply(V)covers the range from 3 V to 5.5 V.The input common mode voltage is from+0.2 V to V_(DD)-0.2 V.Measurement results show that the amplifier has a power rejection ratio of 62 dB and a common-mode rejection ratio of 112 dB.At room temperature,the amplifier has a residual offset voltage of 4.2μV and an effective input-referred noise of 5.81μV in the bandwidth from 1 Hz to 400 Hz with a 4 V power supply.

关 键 词：低频噪声 失调电压 斩波技术 自归零技术 乒乓结构 

分 类 号：TN432[电子电信—微电子学与固体电子学]