A 94 GHz double-balanced mixer for direct up-conversion using 90 nm CMOS technology is reported. The mixer adopts an enhanced double-balanced Gilbert cell with PMOS negative resistance compensation for conversion gain (CG) enhancement and simplified modified derivative superposition in the transconductance stage for linearity improvement. In addition, an output buffer amplifier is included for loading effect suppression, CG enhancement and power consumption reduction. The mixer consumes 8.5 mW and achieves LO-port and RF-port input reflection coefficient better than ?10 dB for frequencies of 81.4---110 GHz and 33.8---105.5 GHz, respectively. The mixer achieves maximal CG of 3.6 dB at 97 GHz, and CG of 2.1 ± 1.5 dB for frequencies of 77.5---100.2 GHz. That is, the corresponding 3 dB CG bandwidth is 22.7 GHz. In addition, the mixer achieves LO-RF isolation of 41.3 dB at 94 GHz. To the authors' knowledge, the CG, LO-RF isolation, power dissipation and matching bandwidth results are one of the best data ever reported for a W-band up-conversion mixer.