Thermal resistance measurements of microwave devices

Temperature influences strongly the electrical behaviour of semiconductor devices, affecting their d.c. characteristics as well as small and large-signal parameters. To determine the junction temperature under thermal steady-state conditions, its thermal resistance has to be known. This paper describes briefly the experimental set-up and procedures developed at the GMA which permit such characterisation of various semiconductor devices including microwave types. As shown in the experimental example, high sensitivity and accuracy of the presented method enables comparative measurements, yielding the thermal resistance value of microwave planar mounting structures.