mm-Wave GaN-on-Si HEMTs with a PSAT of 3.9W/mm at 28GHz

We demonstrate GaN-on-Si HEMTs capable of meeting mm-wave requirements. We compare the large-signal performance for thin barrier AlGaN/GaN and InAlN/GaN-based HEMTs with gate lengths downscaled to 70nm at 28GHz using passive load-pull characterisation. The 8x25µm InAlN/GaN devices with a 100nm gate length achieve a P SAT of 2.8W/mm and a corresponding PAE of 50% at 28GHz at 10V operation in class AB, thereby showing their suitability for power amplifiers in battery-powered user equipment at mm-wave. Finger width reduction for these 8-finger InAlN/GaN devices boosts the normalised P SAT up to 3.9W/mm at a 150nm gate length.