Operational Transconductance Amplifiers (OTAs) are essential building blocks in analog circuits. Since the early years of integrated circuit science, OTAs have been used in industry and researched in academia. Over the years, a number of techniques and approaches to OTA design have been observed in the literature. With this systematic review, we aim to provide a overview of top  journal papers published from 2017 to 2021 containing OTA design. In our investigation we initially found 128 manuscripts and 24 primary studies of OTA design. A set of 10 different techniques have been found. Furthermore, we also evaluate used technology, inversion level and characterization process. With this study we contribute to highlight recent OTA design innovations.

In manufacturing processes of integrated differential amplifiers, an inherent characteristic is that the fabricated nMOS and pMOS transistors have physical differences in relation to the projected values, an effect known as mismatch. In this work, the manufacturing process variations in operational transconductance amplifiers (OTA) are evaluated. Two OTA based on CMOS inverters are designed using both low threshold and standard threshold uniformly doped transistors using quantitative experimental research.