Global Modeling Analysis of HEMTs by the Spectral Balance Technique

A global physical/electromagnetic high electron-mobility transistor (HEMT) simulation approach, entirely in the frequency domain, is here described for microwave computer-aided design applications. The frequency-domain spectral balance technique for the solution of steady-state nonlinear differential equations is applied to the moments of Boltzmann's transport equation for the analysis of the intrinsic active part of the device, yielding a very simple formulation. A numerical electromagnetic solver in the frequency domain is used for the analysis of the extrinsic passive embedding and access structure. The two analyzes are coupled, and give a self-consistent global description of the device. The frequency-domain formulation allows easy inclusion of frequency-dependent parameters of the semiconductor, and a natural extension to multitone analysis, without the need for cumbersome time-frequency transformations. The technique is applied to a quasi-2-D hydrodynamic modeling of the active device for simplicity, but is suitable for more comprehensive approaches as well. DC and small-signal microwave results up to 40 GHz are obtained for a 0.3-mum gate-length AlGaAs-InGaAs-GaAs pseudomorphic HEMT transistor, and compared to experimental data.