CMOS OTA compensating transconductance linearity with PMOS path

Abstract

This paper describes a modified linear operational transconductance amplifier (OTA). We employ the PMOS input stage and PMOS mobility compensation circuit that combines the transistor paths operating at the triode region and subthreshold region that it extends input range to 50% of supply voltage. The circuit enhances linearity of the transconductance (Gm) under the wide input voltage range. The OTA is implemented using a 0.18-mum n-well 1P5M CMOS process under 1.8-V supply. The proposed OTA shows 1% Gm variation and the total harmonic distortion (THD) of below -43-dB under the input range of plusmn0.9-V.