GaAs MMIC pHEMT gate metal thermometry

A thermal resistance measurement technique which exploits the thermal response of a GaAs pHEMT's gate metal resistance is examined. It is found that gate leakage (hole) current due to impact ionization can interfere with the measurement, but can be avoided with correct choice of bias. Measurements and thermal simulations conclude that the bias dependence of the channel heat source profile needs to be considered to improve the accuracy of channel temperature estimation.