A power amplifier MMIC based on AlGaN/GaN HEMTs was fabricated and measured. The coplanar balanced amplifier consists of two 8×100μm transistors. Wilkinson splitters were used to divide and combine the power. By biasing the amplifier at VDS=30V a maximum CW output power of 39dBm corresponding to 5W/mm with a maximum power added efficiency (PAE) of 33.8% was achieved at 10GHz. Biasing the amplifier at VDS=20V resulted in 36.7% PAE with 37.2dBm CW output power at 10GHz. To the authors' knowledge these results represent the highest output power density so far achieved for GaN-based MMICs at X-band in CW mode.
