Self-consistent electrothermal modeling of class A, AB, and B power GaN HEMTs under modulated RF excitation

This paper presents an accurate and flexible approach to the self-consistent electrothermal modeling of III-N-based HEMTs, combining a temperature-dependent electrical compact model with a novel behavioral nonlinear dynamic thermal model, suitable for circuit-level simulations. The behavioral thermal model is extracted, according to a Wiener-like approach, from a full-scale, finite-element-method-based time-domain 3-D solution of the heat equation. The electrothermal model, validated against dc, pulsed dc, S-parameter and large-signal nonlinear measurements, is exploited to assess the impact of thermal memory effects on the device RF performances. In particular, the model allows for a detailed analysis and interpretation of the thermal memory effects on intermodulation distortion. Finally, the proposed approach enables to analyze such features for different thermal mountings, thus providing useful indications for technology assessment.