30-GHz-band over 5-W power performance of short-channel AlGaN/GaN heterojunction FETs

This paper describes the small-signal characterization through delay-time analysis and high-power operation of the K a-band of AlGaN/GaN heterojunction field-effect transistors (FETs). An FET with a gatewidth of 100 mum and a gate length of 0.09 mum has exhibited a current gain cutoff frequency (f(T)) of 81 GHz, a maximum frequency of oscillation (f max) of 187 GHz, and a maximum stable gain of 10.5 dB at 30 GHz (8.3 dB at 60 GHz). Delay-time analysis has demonstrated channel electron velocities of 1.50 x 10(7) to 1.75 x 10(7) cm/s in a gate-length range of 0.09-0.25 mum. State-of-the-art performance-saturated power of 5.8 W with a linear gain of 9.2 dB and a power-added efficiency of 43.2%-has been achieved at 30 GHz using a single chip having a gatewidth of 1.0 mm and a gate length of 0.25 mum.