A 250-μW, 18-nV/rtHz current-feedback chopper instrumentation amplifier in 180-nm cmos for high-performance bio-potential sensing applications

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• 作者：Hyun-Sik Lee ; Van Nhan Nguyen ; Xuan Lap Pham…
• 关键词：Instrumentation amplifier ; Current ; feedback ; Power efficiency ; Bio ; potential sensing ; Chopping ; 1/f noise
• 刊名：Analog Integrated Circuits and Signal Processing
• 出版年：2017
• 出版时间：January 2017
• 年：2017
• 卷：90
• 期：1
• 页码：137-148
• 全文大小：
• 刊物类别：Engineering
• 刊物主题：Circuits and Systems; Electrical Engineering; Signal,Image and Speech Processing;
• 出版者：Springer US
• ISSN：1573-1979
• 卷排序：90

文摘

This paper presents a low-power, high-performance current-feedback instrumentation amplifier (CFIA) for portable bio-potential sensing applications. Noise analysis is performed to assign an optimized current for the input stage of the amplifier. Analysis on selecting nested chopping frequencies is performed, further reducing 1/f noise and the residual offset. Enhanced power efficiency is achieved by sharing cascode branches and using a Class-AB output stage. Through these methods, a good balance between noise performance and other parameters such as output ripples and power consumption of the ripple reduction feedback loop (RRFL) is achieved. The amplifier is developed using a 1-poly 6-metal 0.18 μm CMOS process. Three gain stages with a gain-boosting input stage provide a low-frequency, open-loop gain >250 dB. When configured to a closed-loop gain of 60 dB, the amplifier achieves a noise voltage density of 18 \({\text{nV}}/\sqrt {{\text{H}}z}\) and a 1/f noise corner of 3 Hz. With a current of 75 μA and a supply voltage of 3.3 V, a CMRR of 110 dB and a PSRR of 120 dB are achieved, with an average input offset of about 6.5 μV. The amplifier achieves a state-of-art noise efficiency factor of 4.2. Practical application of the CFIA is demonstrated with an in vivo electrocardiogram detection.