Analyzing A High Gain, Low Power OTA for Biomedical applications in 180 nm CMOS Technology

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, a Fully Differential Two-Stage OTA is introduced in this paper to achieve high DC gain and high Unity-gain frequency. Operational Transconductance Amplifier operates at ± 0.2 V supply voltage, the bias current of 20µA, and achieves a high gain of 74dB. The design comprises a 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 CC > 0.22 CL. The proposed high gain stage achieves additional gain with reduced noise of 0.2 mV/\(\sqrt{\text{H}\text{z}}\) 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.