A Design-Oriented Model for AlGaAs/GaAs and AlGaN/GaN HEMT—Part I

This work presents design-oriented model of dc and ac AlGaAs/GaAs and AlGaN/GaN-based high-mobility field-effect transistors (HEMT) for circuit simulation. The electrostatics of the 2-D electron gas (2-DEGs) at the heterojunction, including the depletion layer, is accurately accounted for without simplifications. Once the electrostatics is correctly devised, the central idea to derive the drain current is to use a second-order symmetric interpolation of the channel charge with respect to the surface potential. It leads to an explicit and continuous expressions of charges and current in all the regions of operation. Apart from this ab initio approximation, no other simplifications are required in the core model: the drain current, terminal charges, potential, and electric field in the channel can be determined exactly. Despite its accuracy, this HEMT model retains the simplicity of industry-standard transistor models. Furthermore, it can be formulated to ensure compatibility with the Penn State Philips (PSPs) model. The model’s accuracy is assessed by comparing it with the exact numerical solution and experiments.