Highly-efficient 6.6 W 12 GHz HJFET for power amplifier

This paper describes successfully developed GaAs-based heterojunction FETs (HJFETs) for Ku-band power amplifier applications with a multi-watt output. The fabricated 0.45 /spl mu/m gate-length HJFET exhibited a maximum drain current of 550 mA/mm, a transconductance of 370 mS/mm, and a gate-to-drain breakdown voltage of 12 V. Power performance for a 1.05 mm gate periphery device demonstrated a maximum output power of 0.81 W with 13.4 dB linear gain and 60% power added efficiency (PAE) at 12 GHz with a drain bias voltage of 7 V. An 8.4 mm HJFET delivered a 5.6 W output power with 13 dB linear gain and 56% PAE at a drain bias of 7 V. At 8 V drain bias, it delivered 6.6 W output power with 12.5 dB linear gain and 50% PAE. These results show the best combination of PAE, gain and output power achieved by a single transistor at this frequency.<>