A Low-Voltage High Linear Body-Driven Operational Transconductance Amplifier and Its Applications

Abstract

Operational transconductance amplifier (OTA) is one of the most significant building-blocks in integrated continuous-time filters. In this paper, we present a body-driven CMOS triode-based fully balanced OTA powered by a single 1.8 V supply. It is linearly tunable with the feature of low distortion and high output impedance. It can achieve wide input range without compromising large transconductance tuning interval. Moreover, a new common-mode feedback scheme has been developed so that the common-mode voltage varies only 7 mV over the tuning range of 1.2 VlesV <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">tune</sub> les1.58 V. Using a 0.18 mum N-well CMOS process, we have implemented a third-order elliptic low-pass filter with the aid of the proposed OTA. The total harmonic distortion (THD) is more than -45 dB for fully differential input signals up to 0.8 V peak-peak (V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">pp</sub> ). Dynamic range of 45 dB is obtained under the OTA noise integrated over 1 MHz.