Two compact, low-power, SiGe W-band LNAs are demonstrated, one single-ended (SE), and one differential (Diff) with an integrated input transformer balun. The LNAs are implemented in an advanced 90-nm SiGe BiCMOS technology, with fT/fmax of 300/350 GHz. The noise figure (NF) of the SE and Diff LNAs are measured to be 4.2 dB and 6.3 dB, respectively, at 94 GHz, while dissipating only 8.8 mW SE from a 2.2-V supply, which to the authors' best knowledge is the lowest reported power consumption for a Si-based W-band SE LNA. The designed LNAs are targeted for low-power phased-array radar integrated transceivers for active imaging applications. The measured gain at 94 GHz for the single-stage SE and Diff LNAs are 10 dB and 12 dB, respectively, and maintain an input reflection coefficient of less than-9.5 dB. The input-1dB compression point (P1dB) for the LNAs is measured to-11.5 and-8.8 dBm for the SE and Diff LNAs, respectively. These compact LNAs have a SE and Diff core size (without pads) of only 158 μm × 350 μm (0.055 mm2 ) and 288 μm × 430 μm (0.126 mm2 ) and the Diff LNA includes an input transformer balun.