This brief presents a W-band 6-bit active phase shifter fabricated in 0.13 μm SiGe BiCMOS process. A wideband quadrature signal generator composed of a 90-degree hybrid and a pair of transformers is exploited for low insertion loss and superior balance. Conventional architecture used in gain control unit is replaced by a novel phase inverter-embedded variable gain amplifier to achieve a high gain and low complexity. In addition, a balun-first combiner with symmetrical layout is utilized at the output to keep as low the imbalance of I/Q paths as possible. The proposed phase shifter exhibits a record average gain of 7 dB at 79 GHz with a 3-dB bandwidth from 71.5 to 84.5 GHz. The variation of gain remains below 2.1 dB over 64 phase states. The measured RMS phase error is 1.35° at 78 GHz and remains below 3.5° from 72 to 82 GHz. The RMS gain error is measured to be 0.46 dB at 75 GHz and keeps less than 0.76 dB from 71 to 82 GHz. The measured input 1dB compression point amounts to -10 dBm. To the best of the author's knowledge, this brief presents the lowest RMS phase error (1.35°) and the highest gain (7 dB) compared with the reported silicon-based W-band active phase shifters.