An X-band GaN HEMT hybrid power amplifier with low-loss Wilkinson division on AlN substrate

The high-power operation of a modular and compact power amplifier (PA) is demonstrated using gallium nitride (GaN) transistors and power-combining networks implemented on an aluminum nitride (AlN) substrate. The power-combining network, tuned for X-Band operation, includes matching circuits and Wilkinson power dividers (WPDs) with tantalum nitride (TaN) thin-film resistors. PA efficiency is increased by minimizing network thermal loss with the AlN substrate, which is an excellent thermal conductor. All system components were mounted on a metal carrier, and were interconnected through gold wire bonds. Large-signal measurements showed power added efficiency (PAE) of 44 % and a peak output power of 6.5 W at 9.5 GHz with a 3 dB fractional bandwidth of 14 %.