A Low-Power Low-Noise Biopotential Amplifier in 28 nm CMOS

A low-power and low-noise bioamplifier for multi-channel electrode arrays (MEA) is presented. Reduction in area and power is achieved by implementing an active lowpass filter without large DC-blocking capacitors, and by employing a small-channel CMOS technology. As the main building block of a 49-channel bioamplifier array designed in TSMC 28 nm CMOS, this bioamplifier has been designed to amplify, filter out the noise outside the useful bandwidth, and extract the action potentials of neural signals. This paper presents a theoretical analysis of noise and power reduction in addition to proposing design tradeoffs. The amplifier occupies an area of 0.003 mm² and consumes 4.6 µW from a 1.8 V power supply. Based on post-layout simulation results, the power, area, and noise characteristics of the proposed design are comparable with the best performance reported to date. The bioamplifier achieves a mid-band gain of 55 dB, a -3 dB bandwidth of 8.75 kHz (from 450 Hz to 9.2 kHz) and an input-referred noise on this band of 10 µVrms.