6-18 GHz, 26 W GaN HEMT compact power-combined non-uniform distributed amplifier

A 6-18 GHz gallium nitride (GaN) non-uniform distributed amplifier (NDA) monolithic microwave integrated circuit with high power density is implemented with compact four-way combined power. The drain lines and gate lines are shared among the combined NDAs. Sharing drain (or gate) lines reduces the drain (or gate) line length by half, while keeping the same characteristic impedances and eliminates bulky and lossy power combiners, such as Wilkinson combiners. The proposed four-way NDA was fabricated using a commercial 0.25 mu m GaN high electron mobility transistor (HEMT) process. It shows average continuous wave output power of 20.8W and average associated gain of 10.7 dB from 6 to 18 GHz under 33 V drain bias. When pulsed input power and pulsed DC bias are simultaneously supplied to the NDA, the output power increases to 26W, on average. To the best of the authors' knowledge, the highest RF power and power density among the reported GaN power amplifiers with an octave bandwidth higher than the Ku-band is represented in this work.