Gallium Nitride HEMTs for Power Amplifiers above 100 GHz

We present work towards D-band (110-170 GHz) Gallium Nitride (GaN) power amplifiers. Source degeneration is investigated for gain boosting at millimeter-wave (mm-Wave) bands for High Electron Mobility Transistors (HEMTs) using the native thru-substrate vias and we describe their role in the degeneration. A 40-nm GaN HEMT is measured and modelled under small-signal, pulsed IV and 94 GHz load-pull. Additionally, we present a 140-GHz power amplifier (PA) in the same 40- nm Gallium Nitride (GaN) process. The PA uses three commonsource amplifier stages and demonstrates a compact, low-loss interstage matching network. The measurements indicate 15.9 dBm of output power, 12 dB of gain, and 9.1% PAE at 140 GHz.