A 3.6 μW 60 nV/sqrtHz Capacitively-Coupled Instrumentation Amplifier for Biopotential Signal Recordings

作者：Zhou, Yin; Wu, Xiaobo; Sun, Peng; Zhao, Menglian^*

来源：Journal of Circuits, Systems, and Computers, 2015, 24(6): 1550089.

DOI：10.1142/S0218126615500899

• Capacitively-coupled instrumentation amplifier
• chopping
• auto-zeroing
• switched-capacitor CMFB

This paper presents a low-power low-noise instrumentation amplifier (IA) intended for biopotential signal recordings. The IA is designed based on a capacitively-coupled topology, which achieves wide input common-mode range, high common-mode rejection ratio (CMRR) and low power consumption. To reduce low-frequency noise and output ripple at the same time, a combination of chopping and ping-pong auto-zeroing techniques, which is normally used in current-feedback IAs, is introduced for the capacitively-coupled topology in this paper. An intrinsic adverse effect of the proposed structure which causes additional ripple is analyzed. The DC electrode offset voltage is suppressed and the input impedance is boosted through feedback techniques. An improved switched-capacitor common mode feedback (SC CMFB) circuit is also presented. Test results show that the IA achieves an equivalent input-referred noise power spectrum density of 60 nV/sqrtHz and a noise efficiency factor (NEF) of 5.58. The bandwidth is 0.5 Hz to 10 kHz, covering most biopotential recording applications. The IA was implemented in 0.18-mu m CMOS process. It occupies 0.27mm(2) core area and consumes 3.6 mu A from a 1V supply.

• 出版日期2015-7
• 单位浙江大学