MOS based pseudo-resistors exhibiting Tera Ohms of Incremental Resistance for biomedical applications: Analysis and proof of concept

Abstract

Performance of biomedical analog circuits vitiates due to non-linear V-R characteristics of Pseudo-resistor (PR) structure, their excess dependency over Process Voltage Temperature (PVT) and common mode variations. In this paper, Incremental Resistance (IR) expressions, V-R curves and statistical results for wider PVT variations for diverse categories of non-tunable and tunable PR structures have been presented. The results obtained using 0.18 μm standard CMOS process with BSIM3V3 device models show that Dynamic Threshold Metal Oxide Semiconductor (DTMOS) technique involving symmetrical biasing for bulk and gate voltages for MOS devices is capable to emulate high nominal value (RYX, N) of IR of the order of 1.95 TΩ over a wider voltage swing of −1 V to 1 V with an area consumption of 60 μm2. Statistical results obtained after performing Monte Carlo Simulations (MCS) with 100 runs for the verification of robustness against PVT variations for this structure shows the value of mean (μ), standard deviation (σ) and Coefficient of variance (CV = σ/μ) as 1.918 TΩ, 100.6 GΩ and 0.052 respectively. Results for a variety of other PR structures reported in this paper can be useful for their possible deployment in circuit applications like neural signal recording and low current sensing etc.