A 2.3-μW Capacitively Coupled Chopper-Stabilized Neural Amplifier With Input Impedance of 6.7 GΩ

Recording electrical activities through high-density electrodes using neural amplifiers plays a crucial role in the successful implementation of a data acquisition system targeting deep-brain regions. To advance the concept of high-density electrodes, neural amplifiers with not only minimum area but also high-power efficiency are needed. This letter presents a neural recording chopper amplifier using the auxiliary path and gain revision techniques to boost the input impedance to a dc value of 6.7 GΩ that meets the requirements of an implantable multichannel recording system. The front-end fabricated in 180-nm CMOS technology occupies an area of 0.051 mm
²
, and consumes a total power consumption of 2.1 μW drawn from a 1-V supply. The proposed work increases the dc input impedance ( 18×) and decreases the area by 25% in comparison with conventional auxiliary path impedance boosting with a CMRR of -75 dB, and the input-referred noise of 2.1 μV
_rms
.