This article presents fully integrated power amplifiers (PAs) with eight-way low-loss power combining for <inline-formula> <tex-math notation="LaTeX">D </tex-math></inline-formula>-band applications in the GlobalFoundries CMOS 45RFSOI process. The eight-way power combining (four-way differential) common source (C.S.) and cascode amplifiers are implemented using four-stage differential PA unit cells as building blocks. The eight-way power combining network is composed of a four-way balun-short-transmission-line (balun-STL) combiner and a conventional quarter wavelength transmission line (QWL TL) combiner. The simulated two-stage eight-way combiner in situ (loaded) ohmic loss is only 1.1-1.4 dB at 130-150 GHz. The eight-way power-combining C.S. amplifier has a small-signal gain of 24 dB at 140 GHz with a 1.2-V supply and a 3-dB bandwidth of 131-150 GHz. The saturated output power (Psat) and output 1-dB compression point (OP 1 dB ) are 16.8-17.5 and 13-14.2 dBm at 130-150 GHz, respectively. The corresponding peak power-added efficiency (PAE) is 11.7%-14.2%. The eight-way power combining cascode amplifier achieves a small-signal gain of 24.8 dB at 135 GHz with a 3-dB bandwidth of 133-148 GHz. The corresponding Psat is 16.3-19 dBm at 125-150 GHz with a peak PAE of 6.5%-12.1%. To the best of our knowledge, these PAs achieve the highest Psat and OP 1 dB at the <inline-formula> <tex-math notation="LaTeX">D </tex-math></inline-formula>-band in CMOS.