A LINEAR OPERATIONAL TRANSCONDUCTANCE AMPLIFIER FOR INSTRUMENTATION APPLICATIONS

A linear operational transconductance amplifier (OTA) is described. It consists of a linear transconductor and a translinear current gain cell followed by three current mirrors. The proposed circuit has superior linearity and temperature characteristic when compared with the commercially available OTA. A prototype circuit with a transconductance of 50-mu-S has been built with discrete bipolar transistors producing a linearity error of less than +/-2% over an input voltage range from -0.8 to 0.8 V. The prototype OTA circuit also exhibits a transconductance that is linearly dependent on a bias current varying over four decades with a sensitivity of 1 S/A.