A 50∼67 GHz double-balanced mixer for direct up-conversion using standard 90 nm CMOS technology is reported. The up-conversion mixer comprises an enhanced double-balanced Gilbert cell with current injection for power consumption reduction, and negative resistance compensation for conversion gain (CG) enhancement, a parallel and differential IF transconductance stage for bandwidth and linearity enhancement, a Marchand balun for converting the single LO input signal to differential signal, and another Marchand balun for converting the differential RF output signal to single signal. The mixer consumes 12.1 mW and achieves IF-port input return loss of −12.8 dB at 0.1 GHz, LO-port input return loss of −9.5 ∼ −11.4 dB and RF-port input return loss of −10.7 ∼ −12.5 dB for frequencies 57∼64 GHz. At IF of 0.1 GHz, the mixer achieves CG of 3.1∼6 dB and LO-RF isolation of 26.4∼30.7 dB for RF of 50∼67 GHz. The corresponding 3-dB bandwidth of RF is larger than 17 GHz (the measurement range of 50∼67 GHz). To the authors' knowledge, the CG and power consumption are one of the best results ever reported for a 60 GHz CMOS/BiCMOS up-conversion mixer.