A 22 dBm, 0.6 mm² D-Band SiGe HBT Power Amplifier Using Series Power Combining Sub-Quarter-Wavelength Baluns

We present a two-stage D-band power amplifier with stacked HBTs and sub-quarter-wavelength baluns as an efficient and compact series power combining technique which leads to a small die area of 0.62 mm² and a record 254 mW/mm² output power per unit die area. The power amplifier has been fabricated in a 90 nm SiGe BiCMOS technology and produces more than 21 dBm output power over the frequency range of 114 - 130 GHz with a peak output power of 160 mW (≈ 22 dBm) at 120 GHz and a 3-dB small signal bandwidth of 35 GHz. To the author´s knowledge, this is the highest recorded power for Si/SiGe BiCMOS process above 100 GHz. This amount of output power is 32% higher than highest prior work while the chip area is 13% the size of that work.