A low-voltage high linear body-driven operational transconductance amplifier and its applications

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 1.8V 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 7mV over the tuning range of 1.2V <= V-tune <= 1.58V. Using a 0.18 mu m 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 -45dB for fully differential input signals up to 0.8V peak-peak (V-pp). Dynamic range of 45dB is obtained under the OTA noise integrated over 1MHz.