A Low-Noise Low-Power Chopper Instrumentation Amplifier With Robust Technique for Mitigating Chopping Ripples
A Low-Noise Low-Power Chopper Instrumentation Amplifier With Robust Technique for Mitigating Chopping Ripples
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一种低噪声低功耗斩波仪表放大器，采用可靠的技术来减轻斩波纹波
DOI：
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发表时间：
2022
影响因子：
5.4
通讯作者：
P. Gui
中科院分区：
文献类型：
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作者：
Liang Fang;P. Gui
电容耦合斩波仪表放大器（CCIA）是设计低噪声、低功耗仪表放大器的经典拓扑结构。然而，CCIA有两个明显的局限性：斩波涟漪和有限的输入阻抗。特别是对于超低噪声应用，CCIA的斩波涟漪很容易使放大器饱和。因此，CCIA设计中需要降低涟漪（RR）。本文介绍了一种新提出的斩波RR技术，动态偏移调零（DOZ）的CCIA。通过在正常斩波操作中引入超低占空比调零阶段，所提出的DOZ技术可以抑制斩波涟漪，测量的最先进的降低率为61 dB，同时引入可忽略不计的噪声、功耗和电路开销。此外，在正反馈回路中采用了一种高线性度的三端变容二极管，使CCIA的输入阻抗达到了1<inline-formula><tex-math notation="LaTeX">μ m以上 ext{G}Omega $</tex-math></inline-formula>。该CCIA采用180 nm CMOS工艺实现，输入参考噪声密度为13 nV/<inline-formula><tex-math notation="LaTeX">$surd $</tex-math></inline-formula>Hz，噪声效率因子（NEF）为1.3，功耗为4.5-<inline-formula><tex-math notation="LaTeX">$mu ext{W}$</tex-math></inline-formula>功率。
Capacitively coupled chopper instrumentation amplifier (CCIA) is a classical topology for designing low-noise, low-power instrumentation amplifiers (IAs). However, CCIA has two significant limitations: chopping ripple and limited input impedance. Especially for ultra-low-noise applications, the chopping ripple of CCIA can easily saturate the amplifier. Hence, ripple reduction (RR) is required in the CCIA design. This article presents a CCIA with a newly proposed chopping RR technique, dynamic offset zeroing (DOZ). By introducing an ultra-low duty cycle zeroing phase in the normal chopping operation, the proposed DOZ technique can suppress the chopping ripple with a measured state-of-the-art reduction ratio of 61 dB while introducing negligible noise, power, and circuit overhead. In addition, a highly linear three-terminal varactor is proposed in a positive feedback loop (PFL) to boost the limited input impedance of the CCIA to be above 1 <inline-formula> <tex-math notation="LaTeX">$ ext{G}Omega $ </tex-math></inline-formula>. The presented CCIA is implemented in a 180-nm CMOS technology and achieves a 13-nV/<inline-formula> <tex-math notation="LaTeX">$surd $ </tex-math></inline-formula>Hz input-referred noise density and a noise efficiency factor (NEF) of 1.3 while consuming 4.5-<inline-formula> <tex-math notation="LaTeX">$mu ext{W}$ </tex-math></inline-formula> power.