Some recent advances and promising results of GaN technology developed by AMS are presented in this work. Due to the wide band-gap properties of this material, these devices are very well suited for high power applications, and must be characterized under strongly non-linear and high power conditions. Pulsed DC characterization and load-pull measurements have been performed on HEMT devices with different layouts and processes, in order to improve and refine the fabrication methodology. AMS devices show a good technology maturity, with performances comparable with state of the art