GaN HFET digital circuit technology for harsh environments

The first demonstration of GaN digital circuits is reported. First-generation GaN digital technology has already shown high yields for circuits of considerable complexity. Specifically, a 31-stage ring oscillator was implemented using 217 transistors. Properties of the AlGaN/GaN material system that enable outstanding power handling capabilities of GaN heterojunction field effect transistors (HFETs), i.e. large bandgap, high breakdown field and high saturation velocity, also make it attractive for digital applications in harsh environments. Because of these unique material characteristics, GaN digital control circuits have the potential to operate in high radiation environments, at elevated temperatures, and directly from high voltage rails. Successful operation of GaN 31-stage ring oscillators at the highest base-plate temperature attainable by the test setup of 265°C, indicates that these circuits can operate at significantly higher temperatures.