Electronically tunable gain instrumentation amplifier using OTAs

This paper presents a simple method for realizing instrumentation amplifier with ease of gain adjustment. The proposed circuit consists of five operational transconductance amplifiers (OTAs) and two resistors in a balancing circuit. The differential gain of the proposed circuit can be electronically varied by changing the external bias currents of OTAs. The high common-mode rejection ratio (CMRR) can be obtained without requiring matched resistors. Experimental results showing the operational characteristics of the proposed circuit are included.