Full W-Band GaN Power Amplifier MMICs Using a Novel Type of Broadband Radial Stub

• Published in: IEEE transactions on microwave theory and techniques 2018-12, Vol.66 (12), p.5664-5675
• Main Authors: Cwiklinski, Maciej, Friesicke, Christian, Bruckner, Peter, Schwantuschke, Dirk, Wagner, Sandrine, Lozar, Roger, Mabler, Hermann, Quay, Rudiger, Ambacher, Oliver
• Format: Article
• Language: English
• Subjects: Bandwidths; Broadband; Broadband communication; Gain; Gallium nitride; gallium nitride (GaN); Gallium nitrides; HEMTs; high-electron-mobility transistor (HEMT); Integrated circuits; Load modeling; Microwave transistors; millimeter-waves (mm-waves); MMIC (circuits); monolithic microwave integrated circuit (MMIC); power amplifier (PA); Power amplifiers; Power efficiency; radial stub; W-band (75–110 GHz)
• ISSN: 0018-9480; 1557-9670
• DOI: 10.1109/TMTT.2018.2878725

In this paper, we describe the design of the first reported full W-band (75-110 GHz) power amplifier (PA) monolithic microwave integrated circuits (MMICs) based on gallium nitride technology. The discussed MMICs come in two versions. Over a bandwidth (BW) of 70-110 GHz, the three-stage PA can deliver, on average, 25.6 dBm with a power-added efficiency (PAE) of 6.5%, while the four-stage PA is able to generate 27 dBm with a PAE of 6.1%. A peak output power of 28.6 dBm is achieved at 80 GHz with a PAE of 8.6%, which corresponds to a power density of 2.6 W/mm. The significant BW was achieved partially by incorporating a novel type of broadband radial stub into the design, which can provide nearly a twofold rejection-BW improvement over the conventional version. To the best of our knowledge, no other solid-state circuit can deliver such power levels over the complete W-band.