A 1.8 V CMOS linear transconductor and its application to continuous-time filters

A 1.8 V body-driven CMOS fully balanced transconductor is presented. It is linearly tunable, possesses low distortion and utilizes a common-mode feedback scheme. Simulation shows common-mode voltage varies only 1.3 mV over the tuning range of 1.2 V < V_tune < 1.58 V. Using 0.18 μm n-well CMOS process, a 3^rd order elliptic low-pass filter is implemented using the proposed transconductor. The total harmonic distortion (THD) is more than -46 dB for fully differential input signals up to 0.8 V peak to peak (V_pp) . with the transconductor noise integrated over 1 MHz, 45 dB dynamic range is obtained.