Abstract

At this time, GaAs PHEMTs exhibit higher power output than InP HEMTs at 60 and 94 GHz. InP HEMTs, however, feature power-added efficiency values that exceed GaAs PHEMTs by about 5 to 20 percentage points at 94 GHz. As a consequence, InP HEMTs remain a superior candidate for millimeter-wave power applications. The reason for the inferior output power of InP HEMTs lies in their relatively small on-state and off-state breakdown voltages. This paper reviews the state of the art of millimeter-wave power HEMT technology as well as recent advances in understanding of breakdown phenomena. It also discusses the prospects and challenges facing InP HEMTs in performance, reliability and low-cost manufacturing.