Performance Analysis of a Subthreshold Differential Amplifier Using JLGAA Verilog-A Behavioral Modeling and Device-Level DG Model

Abstract

This study investigates the design, modeling, and simulation of an ultra-low-power nanoscale subthreshold differential amplifier optimized for biomedical signal acquisition systems, particularly for electrocardiogram (ECG), electromyogram (EMG), and electroencephalogram (EEG) applications. The proposed architecture exploits the subthreshold conduction regime to achieve high intrinsic gain, enhanced energy efficiency, and robust signal integrity when processing low-amplitude biosignals. For accurate electrophysical characterization, the BSIM-CMG model is employed for multi-gate devices, specifically Double-Gate MOSFETs, while a custom-developed Verilog-A model is utilized to capture the behavior of Junctionless Gate-All-Around (JLGAA) transistors. The methodology encompasses comprehensive theoretical modeling and circuit-level simulation, including detailed analysis of device operation in the weak inversion regime and the implementation of a fully functional subthreshold differential amplifier. Simulation results validate that the proposed design satisfies the stringent requirements for power efficiency, linearity, and gain stability in wearable and implantable biomedical systems, offering a viable solution for next-generation ultra-low-power analog nanoelectronic circuits.