In this paper, the impact of self heating on the
linearity of a polar transmitter, with a saturated GaN HEMT
switched mode power amplifier (PA) as final RF stage, is
studied. The thermal circuit parameters of a commercial GaN
HEMT device were extracted in order to evaluate the
temperature rise dependence on power dissipation. A
temperature dependent characterization of the PA modulation
profiles was realized and its behaviour under two tone
excitations with different frequency spacing was obtained
through measurements and simulations, being the self heating
effects clearly masked by other nonidealities, as the case of
feedthrough. In this sense, linearization techniques as
memoryless digital predistortion and I/Q vector hole punching
were applied to the two tone excitation with the aim of
extracting the real self heating contribution. Finally,
temperature dynamics influence on the system residual
distortion under a real communication signal excitation is
shown
