Influence of parasitic effects of the “3ω” measurement setup to improve the determination of GaN HEMTs thermal impedance

The thermal impedance of Gallium Nitride based High Electron Mobility Transistors (GaN HEMTs) has been characterized using the “3ω method”. We already demonstrated in a previous work that, subject to certain conditions, the voltage oscillation at the third harmonic is the real image of the thermal impedance of the device. In this work, we propose both a theoretical approach to understand the limitation of the 3ω test bench and a comparison with measurements especially when power HEMTs are used as the resistance to be measured.