Multi-scale thermal analysis of GaAs RF device

A multi-scale modeling approach is proposed and employed to investigate thermal issues in GaAs MMIC. Thermal analysis down to the signal transistor level was made possible with the development of this approach using the finite element technique. The multi-scale modeling results are then verified with an infrared temperature measurement technique (infrared micro-thermal imaging technique). Both modeling and experiment results have shown that due to its intrinsic low thermal conductivity, self-heating of the GaAs MMIC chip is very localized around the FET gate fingers especially concentrated within the output stage of the GaAs RF device. Thermal management solutions at both the package and system level are needed to keep chip operating temperature under the maximum allowable channel temperature of the device. Steps involved with the multi-scale thermal modeling and parameters affecting thermal characteristics of GaAs MMIC are also discussed.