A Compact Ultrabroadband Stacked Traveling-Wave GaN on Si Power Amplifier

The design and implementation of a GaN stacked distributed 2–19GHz monolithic microwave integrated circuit (MMIC) power amplifier (PA) is presented in this paper. The PA architecture uses six distributed cells, each containing a stack of three transistors. A design method that employs capacitance compensation is presented and applied to a 5–10-W PA design for the 2–19-GHz range in a 100-nm GaN on Si technology. The resulting measured performance at 28-V supply shows a gain flatness of 20.5 ± 1.5 dB, with an output power of 37.4–40.9 dBm and corresponding poweradded efficiency of 22%–49% over the entire frequency range. To the best of the authors’ knowledge, this is the first demonstration of a GaN on Si stacked distributed MMIC PA, with a die size of $2.8\times1.7$ mm 2 and with a maximum power density of 2.58 W/mm 2 over chip area.