RF waveform engineering applied to GaAs MESFET radiation safe operating area

This paper gives an overview on tests done at ESA/ESTEC related to the safe operating area of two different types of GaAs MESFET when subjected to heavy ion bombardment while loaded with RF signal. The heavy ion test campaigns are described and waveform measurements defining the safe operating area for the two types of devices are discussed. The principal interest of performing radiation tests under RF conditions is to reach regions which would not be testable in DC conditions, albeit being reached by application voltage waveforms. The results show very different robustness characteristics depending the MESFET process selected and show that, as opposed to commonly believed, GaAs devices may not be fully immune to burn outs under heavy ion conditions.