In-Situ Extraction of the Thermal Impedance of GaN Power HEMTs Embedded in PCB-based Power Circuits

This paper validates an innovative thermal impedance (Z(TH)) extraction technique against a state-of-the-art GaN-based power HEMT embedded in a PCB-based power circuit. Differently from traditional approaches based on direct or indirect temperature measurements, the technique provides the junction-to-ambient Z(THj-a)- that is, the in-situ Z(TH) - without any need for (i) thermocouples/infrared cameras or (ii) specific equipment like thermochuck and cold-plates. The accuracy of the technique is assessed by adopting the `simulated experiments' strategy: the technique is applied to calibrated electrothermal simulations emulating the experiments, and the extracted junction-to-ambient Z(TH) is successfully compared to a reference one preliminarily determined with numerical simulations.