Design of a Linear CMOS OTA with Wide Input Voltage Range

This paper describes a new linear operational transconductance amplifier (OTA) operating under wide input voltage range. To improve the linearity of the OTA, we employ a mobility compensation circuit that combines the transistor paths operating at the triode and subthreshold regions. The common-mode control circuit consists of a common-mode feedback and common-mode feedforward. The circuit enhances linearity of the transconductance (Gm) under the wide input voltage range. The proposed OTA shows plusmn1% Gm variation and the total harmonic distortion (THD) of below -73-dB under the input range of plusmn1.1-V. The OTA is implemented using a 0.35-mum n-well CMOS process under 3.3-V supply