This paper presents an ultra-wideband frequency quadrupler formed of two polyphase frequency doublers sandwiching a balanced power amplifier. Quadrature phases are employed to suppress undesired harmonics that fall within the bands of interest. Implemented in 22nm FDSOI technology, the proposed quadrupler operates from 74 to 140 GHz, achieving 66 GHz bandwidth and 62% FBW, with a peak saturated output power of 4.8 dBm at 120 GHz. To the authors’ knowledge, the proposed design has the highest reported fractional bandwidth to date, compared to non-distributed CMOS and SiGe quadruplers, while delivering an output power above 0dBm and a harmonic suppression higher than 21 dB.