An ultra-wideband, hybrid, distributed power amplifier using flip-chip bonded GaN devices on AlN substrate

In this paper, the authors present an ultra-wideband hybrid distributed power amplifier, making use of discrete gallium-nitride devices. The design facilitates flip-chip bonding on aluminum-nitride substrate, as well as capacitive division at the input of the devices for bandwidth extension; and non-uniform drain and gate artificial transmission lines for power and efficiency optimization. Measured results show 11 dB gain, and over more than a decade 3-dB bandwidth from 0.4 GHz to 8 GHz. Under pulsed operation with 10% duty-cycle and for an input power of 31 dBm, the measured output power ranges across this bandwidth from 38dBm to 41 dBm, and the power-added efficiency varies from 18% to 45%. To the authors´ knowledge, these results demonstrate the widest bandwidth for a hybrid, distributed power amplifier in gallium-nitride technology.