K-band 0.25 μm GaN HEMT

DC and RF performances of 0.25 μm GaN HEMT on sapphire with T-shaped gate (W
g
= 8×50 μm) based on the AlGaN/AlN/GaN heterostructure are presented. The measured figures of merit are f
T
= 31 GHz and f
max
= 60 GHz. A transistor's small signal equivalent circuit is extracted.