Analysis of drain-current nonlinearity using surface-potential-based model in GaAs pHEMTs

In this paper, we present a physics-based model for accurate simulation of intermodulation distortion (IMD) in GaAs pseudomorphic HEMTs at 2 GHz. We combine the surface-potential-based drain-current model previously developed by us with the standard topology used in these devices for accurate nonlinear simulations. The proposed model is in excellent agreement with measured IMD data at multiple dc bias points varying from close-to cutoff voltage to the high-conduction region. We also analyze the impact of various model elements and physical effects on IMD behavior of the device. Furthermore, the popular Volterra series coefficients for the drain current nonlinearity are analyzed and their relative importance with respect to the overall device nonlinearity is assessed.