A low-power W -band (75-110 GHz) doublebalanced up-conversion mixer using a 0.13 µm SiGe:C BiCMOS technology with f T / f max = 250/370 GHz is presented. The mixer includes ON-chip transformer baluns at the LO and RF ports for on-wafer characterization. At 91.3 GHz, the active mixer achieves a single sideband (SSB) power conversion gain of 4.1 dB with a 3-dB RF bandwidth (BW) of 30 GHz from 78.1 to 108.3 GHz, covering almost the entire W -band. The linearity performance, characterized by OP 1dB and P sat , is 0.6 and 1.8 dBm, respectively while consuming only 11 mW from a 1.8 V supply. Moreover, a second-order IF LC low-pass filter (LPF) with a cutoff frequency of 1.4 GHz is integrated to provide an additional spurious suppression of ∼12 and ∼19 dB at the second and third harmonic of the fundamental IF (i.e., 1.25 GHz). The overall chip area, including the IF LPF is 990 × 540 µm (0.53 mm 2 ). To the best of authors' knowledge, the active up-conversion mixer achieves the lowest power consumption along with the highest OP 1dB / P sat and 3-dB RF BW reported among all prior published W -band SiGe-HBT up-conversion mixers.