A Low-Power Low-Noise Neural Recording Amplifier With Improved Telescopic-Cascode OTA

Abstract

In this paper, a fully-differential low-power low-noise neural recording amplifier with a novel recycling telescopic-cascode (RTC) operational transconductance amplifier (OTA) is presented. In the proposed RTC-OTA, the current recycling and positive feedback cross-coupled transistors are utilized to significantly improve the OTA's parameters such as DC gain and unity gain bandwidth. The gain enhancement also improves the linearity in the closed-loop structure. Extensive analytical calculations and simulation results using the $\boldsymbol{0.18-\mu \mathrm{m}}$ TSMC CMOS process are provided to evaluate the usefulness of the proposed OTA. The simulated neural recording amplifier achieves 4.46 $\boldsymbol{\mu \mathrm{V}_{\text{rms}}}$ input-referred noise over 1 Hz-10 kHz bandwidth, 1.82 noise efficiency factor, -46 dB total harmonic distortion (THD) for an 18 $\boldsymbol{\text{mV}_{\text{pp}}}$, 1kHz sinusoidal input. The power consumption is 2.25 $\boldsymbol{\mu \mathrm{W}}$ from a 1.8-V voltage supply.