Efficient AlGaN/GaN HEMT Power Amplifiers

This paper describes efficient GaN/AlGaN HEMTs and MMICs for L/S-band (1-4 GHz) and X-band frequencies (8-12 GHz) on three-inch s.i. SiC substrates. Dual-stage MMICs in microstrip transmission-line technology yield a power-added efficiency of ¿40% at 8.56 GHz for a power level of ¿11 W. A single-stage MMIC yields a PAE of ¿55% with 6 W of output power at V_DS= 20 V. The related mobile communication power HEMT process yields an average power density of 10 W/mm at 2 GHz and V_DS= 50 V. The average PAE is 61.3% with an average linear gain 24.4 dB and low standard deviation of all parameters. The devices yield more than 25 W/mm of output power at 2 GHz when operated in cw at V_DS= 100 V with an associated PAE of ¿60%. The GaN HEMT process with 0.5 ¿m gate-length yields an extrapolated lifetime of 10⁵ h when operated at V_DS= 50 V at a channel temperature of 90°C. When operated at 2 GHz devices with 480 ¿m gate-width yield a change of the RF power-gain of less than 0.2 dB under high gain-compression at V_DS= 50 V and a channel temperature of 250°C.