The operational transconductance amplifier (OTA) is an opamp that produces an output current proportional to its differential input voltage. OTAs are similar to a standard operational amplifier in that it has high impedance differential inputs and the OTA may be used with negative feedback. An OTA can be thought of as an operational amplifier without the output stage. Inside a mixed signal ASIC, OTAs can often replaces standard opamps because there is not the need to drive large capacitive loads within the IC. Therefore, an OTA-based circuit can be smaller, higher performance and use less power than an all opamp circuit. This is one of their areas where semiconductor implementations vary significantly from printed circuit board (PCB) implementations. Discrete opamps need “over designed” output stages to insure that the opamp will work in a wide variety of output load applications. Since standard product manufacturers do not know these output load situations ahead of time the opamp contains high-power and larger output drive circuitry.

Triad engineers have experience designing operational amplifier and OTA IP with unity gain bandwidths from kHz to GHz. Triad’s IP library contains hundreds of OTA options covering a wide variety of process nodes, foundries and operational voltage ranges. Collectively, our design team has over 600 years of custom IC design experience. Our OTAs are designed for demanding specifications in the areas of input referred noise, ultra wide gain bandwidth, high voltage operation, etc. Please click the [ contact ] button in the main menu to email one of our ASIC architects to discuss you mixed signal integration needs.