An 81 GHz, 470 mW, 1.1 mm2 InP HBT power amplifier with 4∶1 series power combining using sub-quarter-wavelength baluns

We report a two-stage W-band power amplifier (PA) using novel 4.1 series power-combining with sub-quarter-wavelength baluns. The power amplifier, fabricated in a 0.25 μm InP HBT technology, produces 470 mW (26.7 dBm) output power at 81 GHz, 23.4 % peak PAE, and >11.5 GHz 3-dB bandwidth. The compact series power-combining networks permit a small 1.06 mm
²
die area and a high 443 mW/mm
²
output power per unit die area.