High efficiency hybrid power amplifier design using heterostructure field effect transistors

The design and performance of high efficiency amplifiers using state-of-the-art Heterostructure Field Effect Transistors (HFET) operating in class AB/F at X-band are presented. Two single-ended power amplifiers were designed using 4.8 mm and 9.6 mm gate width HFET devices. Conventional MIC technology was employed for practically realising the designs. Excellent agreement between simulation and measurements were achieved. The amplifiers produced power-added efficiencies significantly higher than conventional power devices. The first amplifier employing the 4.8 mm HFET achieved a power-added efficiency of 53 percent at an output power of 2.5 W and having 8 dB small-signal gain. The second amplifier employing the 9.6 mm HFETs achieved a power-added efficiency of 42 percent at an output power of 8 W and having 7 dB small-signal gain.