A 3-10-GHz GaN-based flip-chip integrated broad-band power amplifier

In this paper, we report the latest progress of a GaN-based broad-band power amplifier using AlGaN/GaN high electron mobility transistors (HEMTs), grown on sapphire substrates, as the active devices. The devices were flip-chip integrated onto the aluminum nitride circuit board for thermal management and electric connection. The circuit topology used novel LCR-matching networks in a four-way binary-Wilkinson combiner structure. Using devices with 0.7-mum gate length and 4-mm gate width, a small-signal gain of 7 dB was obtained with 3-10-GHz bandwidth. Output power of 8 W (continuous wave) at 9.5 GHz with about 20% power-added efficiency was achieved when biased at 24 V,which is the highest output power for a power amplifier using GaN-HEMTs-on-sapphire.