Implementation of High-Power-Density X -Band AlGaN/GaN High Electron Mobility Transistors in a Millimeter-Wave Monolithic Microwave Integrated Circuit Process

• Published in: IEEE electron device letters Vol. 36; no. 10; pp. 1004 - 1007
• Main Authors: Fitch, Robert C., Walker, Dennis E., Green, Andrew J., Tetlak, Stephen E., Gillespie, James K., Gilbert, Ryan D., Sutherlin, Karynn A., Gouty, William D., Theimer, James P., Via, Glen D., Chabak, Kelson D., Jessen, Gregg H.
• Format: Journal Article
• Language: English
• Published: IEEE 01.10.2015
• Subjects: AlGaN; Aluminum gallium nitride; field-plate; Gallium nitride; GaN; HEMTs; high electron mobility; Ka-band; Logic gates; MMICs; MODFETs; transistor; Wide band gap semiconductors; X-band; field-plate; GaN; high electron mobility transistor; X-band; SiC; Ka-band; AlGaN
• ISSN: 0741-3106; 1558-0563
• DOI: 10.1109/LED.2015.2474265

A GaN high electron mobility transistor monolithic microwave integrated circuit (MMIC) designer typically has to choose a device design either for high-gain millimeter-wave operation with a short gate length, or for high-power-density X-band operation with a much larger gate/field-plate structure. We provide the designer the option of incorporating two different devices by implementing a 0.14-μm gate length GaN MMIC process capable of high-efficiency Ka-band operation while simultaneously achieving high power density in the same process flow. The key process enabler simply uses the capacitor top plate in the MMIC process as a field plate on the passivation layer. On two separate devices on the same chip using the same MMIC process flow, we demonstrate 7.7 W/mm at 35 GHz and V DS = 30 V on a standard 4 × 65-μm T-gated FET and then 12.5 W/mm at 10 GHz and V DS = 60 V on a 4 × 75-μm T-gated FET by adding a field plate. These are the highest reported power densities achieved simultaneously at X-band and Ka-band in a single wideband GaN MMIC process.