Linearity Enhancement Techniques for Operational Transconductance Amplifier: A Survey

Background: Operational Transconductance Amplifier (OTA) plays an essential role in many analog and mixed-signal applications that encourages the researchers to contribute their work to design suitable structures of OTA for their applications with acceptable performance parameters. Methods: The linearity of an OTA is one of its key performance parameters, which affects the performance of the overall system whereas the transconductance value of OTA (Gm) contributes to decide its application area. Low transconductance OTA finds its application in biomedical and neural networks while OTA with higher transconductance is suitable for wireless communication. In any system, it is desirable to obtain a linear voltage-to-current conversion, i.e., OTA, hence various linearization techniques have been reported to linearize the OTA. Results: In the last two decades, various OTA structures have been reported with linear voltage-tocurrent conversion. Some researchers used attenuation by means of different circuit approaches to linearize the OTA or some used cancellation of nonlinearity terms by using different circuit implementation techniques. Researchers used some other methods also to linearize the OTA viz source degeneration, square root technique and mobility compensation. Conclusion: The purpose of this paper is to provide a brief survey of various popular linearization techniques reported in the past.