Hydrogen sensitivity of GaAs HEMT amplifiers: the effect of bias mode

The effect of hydrogen incorporation is well known to degrade the performance of GaAs HEMT transistors. The main source of hydrogen is in the plated internal metal surfaces of a hermetic enclosure used to package GaAs MMICs. We have found a new circuit technique for hydrogen mitigation, which may be useful under certain circumstances - use of a current regulation scheme for each transistor in a MMIC. The value of this method is that even under extremely high levels of hydrogen and accelerated temperature conditions where the HEMTs are expected to fully saturate with hydrogen, the net effect on RF gain degradation can be minimized to a tolerably low level.