Characterisation of GaAs pHEMT Transient Thermal Response

Abstract

Transient gate resistance thermometry is employed to characterise the time domain response of a GaAs pHEMT under pulsed conditions. Self heating is observed from hundreds of nanoseconds to hundreds of milliseconds. A TFR-heated test structure is used to develop a 3-D finite-element thermal model that scales with power density and gate periphery. Thermal coupling between gate fingers in a multi-finger device is measured, and then further investigated via simulation. The model's application to thermal optimisation of devices and circuits is discussed.