This paper presents two MMIC broadband high power amplifiers of 4 mm of periphery at the output stage in the frequency band 2-6 GHz. The amplifiers are based on AlGaN/GaN high electron mobility transistor (HEMT) technology on SiC substrate. They have been fabricated in two different european foundries: SELEX Sistemi Integrati and QINETIQ. SELEX has a gate process technology of 0.5μm, and devices of 10x100μm periphery in microstrip technology and QINETIQ has a gate-length of 0.25μm, and devices of 8x125μm in coplanar technology. The coplanar amplifier from QINETIQ has demonstrated an output power of 8W in continuous wave at V ds =20V which confirm model predictions. On the other hand, SELEX microstrip amplifier has a saturation power of 10W CW at V ds =25V and 4 GHz. This amplifier measured on-wafer in pulsed conditions exhibits a maximum power of 17W at V ds =30V.

This paper describes and evaluates two MMIC broadband high power amplifiers in the frequency band 2-6 GHz in microstrip technology. These amplifiers have scalable output-stage periphery of 4 and 8 mm. The amplifiers are based on 1 mm AlGaN/GaN high electron mobility transistor (HEMT) technology on SiC substrate. They were fabricated in the European foundry SELEX Sistemi Integrati, which has a gate process technology of 0.5 μm. The 4 mm amplifier has exhibited an output power of 15 W and the 8 mm of 28 W at Vds=25 V in pulsed conditions. The best power performance in continuous wave are 10.5 W and 15 W for 4 mm and 8 mm, respectively. Better than 20% PAE over the 2-6 GHz frequency range is achieved in CW.

AlGaN/GaN HEMT TechnologyFirst of all, MMIC GaN technology has to be evaluated. High power GaN devices operate at high temperature and high-dissipated power due to the high power density of performance. Therefore, the use of substrates with high thermal conductivity like the silicon carbide (SiC) is preferred. GaN technological process is still immature and complex. However, gate lithography resolution lower than 0.2 m and AlGaN/GaN epi-structures on 100-mm SiC substrates are already available (Milligan et al., 2007). 22www.intechopen.com