A Nonlinear Model of RF Switch Device Based on Common Gate GaAs FETs

Abstract

This paper presents a novel method for nonlinear modeling GaAs field-effect transistors (FETs) in a common gate (CG) configuration, which is crucial for the effective design and thorough assessment of RF switch circuits. By focusing solely on a CG-based GaAs FET for RF switch device characterization and modeling, the modeling process is streamlined compared to traditional methods that involve both CG and common source (CS) devices. The direct measurement of both DC and RF characteristics using the CG device enhances the accuracy of model parameter extraction. This approach ensures consistency in model and simulation applications as the CG topology aligns with devices commonly found in RF switch circuits. Moreover, to enhance predictive accuracy regarding the dispersion effect, an improved equation of drain-source current has been incorporated. The empirical validation of the model reveals good agreements in terms of insertion loss, isolation, and output power performance for the CG GaAs FET device, including a wide band single-pole double-throw (SPDT) switch Monolithic Microwave Integrated Circuit (MMIC).