A 1.1 μW biopotential amplifier based on bulk-driven quasi-floating gate technique with extremely low-value of offset voltage

Biopotential amplifier (BPA) remains one of the most crucial blocks for the successful implementation of any of the biomedical systems. However, design of a BPA remains challenging owing to most of the topologies reported in literature displaying high values of noise, consuming high value of power and working in limited range of bandwidth. Thus, circuit topologies capable of providing an optimum and an acceptable combination of these parameters remains a topic of immense interest among researchers. We in this paper, report the results of a BPA designed using Bulk-Driven Quasi-Floating Gate (BDQFG) technique with a special focus on the effect of variation in the values of biasing resistor (Rlarge). Results obtained through mathematical modelling and analysis of the circuit have been verified by conducting simulations in Cadence Analog Design Environment using standard 0.18 µm technology. Circuit design has been optimized for least values of power consumption of the order of 1.1 µW, noise (≈ 3.15 µVRMS), mid-band gain of 39.9 dB (from 0.266 Hz to f-3dB of 2.8 kHz), offset voltage of 455 μV and phase margin of 65.83°.