On Low Power CMOS Operational Transconductance Amplifier Structures

Emerging field of System on Chip(SoC) design require powerful on chip mixed signal processing capability that require powerful analog signal processing block along with the logic processing digital block. These powerful analog IC design capabilities are also required in many battery operated, low power-low frequency applications The growing demand of low power, portable and biomedical devices require low power low noise analog ICs. These analog ICs use Operational Transconductance Amplifiers or OTA as they are generally called, as their main component. OTAs are special type of Operational Amplifiers that have additional capability of tune able gain along with higher output impedance. The OTAs are used as basic building blocks in Alalog IC designing. In this article, four different OTA structures are reviewed with high DC gain, high speed, linearity and design flexibility. We have reviewed architecture of power optimized OTA’s with respect to their usability as active filters, as programmable CMOS-OTA, and analog and mixed analog-digital signal processing systems.