RF Extraction of Thermal Resistance for GaN HEMTs on Silicon

In this article, an ac conductance method has been successfully employed to extract the thermal resistance of GaN-based high-electron-mobility transistors (HEMTs) on silicon. The resulting thermal resistances, when varying the channel length and gate width, are comparable to those obtained with pulsed measurements, by making use of positive drain-to-source pulsed voltages from a zero power dissipation quiescent bias point and 3-D thermal simulations. Furthermore, the gate geometry dependence of the thermal resistance of GaN-based HEMTs has been successfully modeled for circuit-design purposes.