High-gain high-power-density stacked GaN HEMTs operating at 140V with reconfigurable inter-stage matching circuit

With the development of GaN HEMTs, solid state power amplifiers are hopeful to replace the vacuum tube power amplifiers in more and more areas. However, the working voltage and power density of GaN HEMTs are still very low. Transistor stacking is a promising solution to ameliorate this problem. In this letter, we combine a unique high-voltage 0.25μm GaN-on-SiC technology and stacking topology together and build a high-voltage high-power-density high-gain GaN stacked HEMTs. Our stacked device combines two 20×120μm GaN HEMTs connected in serial to work at 140V. The output power and gain of the stacked device are 45.6dBm and 17dB, respectively, at 3GHz and 100μs pulse width/10% duty cycle. The power density reaches about 15W/mm, increased by about 41% compared with state-of-the-art stacked devices. To the author’s best knowledge, this is the highest power density and highest working voltage among microwave stacked transistors.