CMOS Tunable Pseudo-Resistor with Low Harmonic Distortion

Abstract

In this work, a tunable pseudo-resistor was designed, simulated, and tested using a 0.35 µm CMOS technology. The proposal used a compact voltage bias circuit free of body-effect, allowing a constant resistance value over the pseudo-resistor’s dynamic range, improving its linearity. A fabricated cell was characterized providing a resistance value from 300 kΩ to 10 GΩ with a THD from <2.5% to 1 GΩ. Additionally, the pseudo-resistor was incorporated into a high-pass OTA filter showing a THD below 0.2% for input voltages in the range ≤ 0.3 Vp. The simulations were compared with experimental measurements in a CMOS-fabricated cell, which verified the proposal’s feasibility.