Improved Operational Trans-Conductance Amplifier for Bio-potential Signals

Abstract

Bio-potential signals are acquired non-invasively using surface electrodes. These electrodes are followed by the pre-amplifiers to provide amplification to these low frequency and low amplitude signals for further processing. This work focuses on the design of the first-stage Operational Trans-Conductance Amplifier (OTA) used as pre-amplifier. Capacitive coupled current mirror OTA is designed to obtain the optimized values of bandwidth, power, noise and area. The modification in feedback circuit elements i.e. pseudo-resistors’ structures, feedback capacitors and coupling capacitors were considered to remove the limitations of non-linearity and large area. The two-series-connected pMOS and back-to-back source connected pMOS structure based pseudo-resistors enhanced the performance of the OTA, whereas, the T-capacitor network based feedback significantly reduced the area of the OTA.