A D-Band GaN Power Amplifier With 28-dBm P sat, a Power Density of 0.2 W/mm2, and Loss-Optimized Matching Networks

In this letter, we present a D-band power amplifier (PA) monolithic microwave integrated circuit (MMIC), manufactured in a gallium nitride (GaN)-on-silicon carbide (SiC) high electron-mobility transistor (HEMT) technology. The PA comprises six stages of 70-nm gate-length HEMTs and features 4-way corporate power combining, which results in an output stage gate-width of 352 µm. We develop and analyze a loss-optimized interstage matching network (ISMN) topology, which is crucial for driving the output stage. As a result, the PA delivers a saturated output power (P <inf>sat</inf>) of more than 25.2dBm between 125 and 151 GHz, and a peak P <inf>sat</inf> of 28 dBm at the center of the frequency band. The high P <inf>sat</inf> and a small chip size (3.125 mm²) translate into a power density (P<inf>dens</inf>) of more than 0.2 W/mm². To the best of our knowledge, this PA MMIC demonstrates the highest P <inf>sat</inf> and P<inf>dens</inf> beyond 120 GHz across all technologies.