FGMOS BASED INSTRUMENTATION AMPLIFIER FOR HEALTHCARE APPLICATIONS

Abstract

This thesis presents a new FGMOS based instrumentation amplifier for bio-medical applications. Instrumentation amplifier is an essential block for most of the bio-medical applications as it extracts out weak potential signals that may lie between microvolt to millivolt from human body. To extract weak potential signal, an instrumentation amplifier is needed to have very high common mode rejection ratio (CMRR) so that it can minimise the effect of common mode noise and hence desired signal can be extracted out. An instrumentation amplifier with high CMRR, high gain and low power dissipation is essentially required. To operate circuit on low voltage, FGMOS is used. FGMOS is a multi-input floating gate MOSFET used to reduce threshold voltage and hence operated on low supply voltage which results in lower power dissipation. Here, FGMOS is used to simulate two stage operational amplifier and hence, by using operational amplifier, instrumentation amplifier is drawn. The main purpose of using FGMOS in the circuit is its smaller threshold voltage compared to the normal MOSFET and having threshold voltage tuning ability. Threshold voltage can be changed by changing capacitance ratio at the gate terminal. Because lower threshold voltage is required for the circuit operation, it consumes low power and is hence suitable for battery powered portable devices. The two stage operational amplifier is designed in virtuoso 90nm technology and operated on 1.8V supply. Also, the two stage operational amplifier based on FGMOS is operated on 1.35V (the minimum voltage requirement of FGMOS based circuit so that all the MOSFET remains in saturation region). Technological parameters table of two stage operational amplifiers are charted out using FGMOS and with conventional MOS.