A High Value, Linear and Tunable CMOS Pseudo-Resistor for Biomedical Applications

Abstract

A subthreshold MOS-based pseudo-resistor featuring a very high value and ultra-low distortion is proposed. A bandpass neural amplifier with a very low high-pass cutoff frequency is designed, to demonstrate the linearity of the proposed resistor. A BJT less CTAT current generator has been introduced to minimize the temperature drift of the resistor and make tuning easier. The standalone resistor has achieved 0.5% better linearity and a 12% improved temperature coefficient over the existing architectures. A neural amplifier has been designed with the proposed resistor as a feedback element. It demonstrated 31[Formula: see text]dB mid-band gain and a low-pass cutoff frequency of 0.85[Formula: see text]Hz. The circuit operates from a 1[Formula: see text]V supply and draws 950[Formula: see text]nA current at room temperature.