Abstract:

As biopotential signals are having very small frequency variations tens of Hz and micro to millivolts amplitude in the range. While acquiring biopotential signals from a human body, intrusions occur in the acquisition system. Thus, for acquiring noise-free signals, the enhanced Biopotential Acquisition unit having a high gain with an improved common-mode rejection ratio readout front-end is designed. To solve mentioned issues, an improved front end is introduced in this paper to achieve high DC gain and high Unity-gain frequency. The proposed front-end operates at ±0.2 V supply voltage, the bias current of 20µA, and achieves a high gain of 74dB. The design comprises a miller frequency compensation structure by connecting a capacitor across a high voltage stage and the load capacitor is connected across output by following the relation of C_C > 0.22 C_L. The proposed high gain stage achieves additional gain with reduced noise of 0.2 mV/  with a minimal power consumption of 1.9 nW. The analog readout front-end is executed using 180 nm CMOS Technology and utilizes less power, making it ideal for battery-powered devices in Biopotential Acquisition systems. The final section includes a comparison of the proposed front-end with various amplifiers.

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