4 GHz high-power high-efficiency pseudomorphic power HEMT

The power performance of 0.25- mu m*8-mm double recessed GaAs-based pseudomorphic high electron mobility transistors (PHEMTs) at 4 GHz is reported. The 0.25- mu m-gate-length PHEMTs exhibit typical gate-to-drain breakdown voltage of more than 20 V, peak transconductance of 430 mS/mm, and maximum drain current density of 450 mA/mm. When the drain was biased up to 11 V, the device delivered 5.7-W output power with 12.6-dB power gain and 57% power-added efficiency (PAE). The device demonstrates an extremely broad drain bias range for efficient operation. It exhibits a maximum PAE of 72% with an output power of 4.1 W under a V/sub DS/=7 V condition. with 8-V drain bias, when the device was tuned for maximum output power, it delivered 4.3 W of P/sub 2dB/ with 15.4-dB power gain and 66% PAE. >