A Highly Linear CMOS Transconductance Amplifier in 180nm Process

Abstract

The present work describes the design and analysis of an operational transconductance amplifier (voltage to current converter) with wide linear input range. In differential amplifier Harmonic distortion due to odd order harmonics because due to differential nature even order harmonics automatically cancel. In differential amplifier odd harmonics terms causes nonlinearity. In operational transconductance amplifier odd harmonics terms causes nonlinearity. Several techniques are there to improve the linearity of the operational Trans conductance amplifier one most of the most popular technique is source degeneration technique .Generally source degeneration techniques obtained by using resistors at the source this provides negative feedback .negative feedback reduces the gain as well as reduce nonlinearity terms. Another technique is attenuator followed by source degenerated differential amplifier .In this technique first stage is attenuator this attenuator gives linear attenuated differential output voltage severs as input to the source degenerated OTA. Using this technique we will get more linearity .another technique is nonlinearity cancellation technique. This technique implemented by using Balanced OTA current expression. . All these operational transconductors are designed and simulated 180nm process technology with 1.8V power supply. Using these techniques linear input range increases and third order harmonic distortion (HD3) is reduced.