Modeling GaN HEMT Devices: Physical Insights into Intrinsic and Extrinsic Circuit Components of the SPICE model

Paper in proceeding, 2026

This paper presents a physics-based interpretation of Gallium-Nitride (GaN) High Electron Mobility Transistor (HEMT) compact modeling by establishing a direct correspondence between the device physical structure and its SPICE circuit representation. The device is decomposed into intrinsic and extrinsic elements, each associated with measurable or physically interpretable mechanisms, to clarify how operating conditions influence circuit-level behavior. The key contribution of this work is the identification of the physical origins of major circuit components and the explanation of how their characteristics vary with applied bias voltages. The analysis relates two-dimensional electron gas (2DEG) transport, field-plate modulation, and metal contact behavior to their corresponding elements in the equivalent circuit, providing clear physical meaning to compact model parameters. Furthermore, the circuit components of a commercial 650 V, 60 A GaN HEMT are extracted using two-port S-parameter measurements. The resulting framework enables more accurate and predictive compact models for reliable loss estimation and switching behavior analysis in GaN power converters.