Record D-Band Performance From Prematched N-Polar GaN-on-Sapphire Transistor With 2 W/mm and 10.6% PAE at 132 GHz

In this letter, we report the first D-band operation of N-Polar GaN technology with record large signal performance using co-planar waveguide (CPW) pre-matching networks. The pre-matched devices were designed without utilizing a large signal model. Load line resistance and output capacitance were extracted from the 94 GHz passive load-pull measurements of equivalent un-matched devices for output pre-matching network design at D-band. These parameters were then further verified with the pulsed-IV and S-parameter measurements. For the input pre-matching network, conjugate matching at the small signal model was achieved. An N-Polar GaN pre-matched device biased at 12 V and 0.5 A/mm showed 2 W/mm (100 mW) output power with 10.6% power-added efficiency (PAE) at 132 GHz, without de-embedding the matching network losses. With matching network losses de-embedded, the power density and PAE at the device level are 2.7 W/mm and 21.8% at 1.6 dB compression, respectively. Device level OP1dB of 2.2 W/mm at 132 GHz closely agrees with OP1dB of 2.3 W/mm measured by 94-GHz load pull, showcasing the excellent output match as well as the saturated power being limited by drive power at 132 GHz. To the best knowledge of the authors, the reported output density of 2 W/mm is the highest reported GaN output power density at D-band.