A 6GHz 3X Subharmonic Mixer with 12.4-dB Conversion Gain and 73-dB Fundamental Rejection

This paper presents a 6-GHz 3×subharmonic down-conversion mixer achieving 12.4-dB peak conversion gain and 73-dB fundamental rejection, the highest reported performance among down-conversion 3× subharmonic mixers. The proposed architecture employs a two-stage fundamental-cancelation scheme consisting of a tunable L-C coarse band-stop network followed by an active feed-forward fine canceler, enabling phase-invariant suppression without requiring multi-phase LO generation or precise phase matching. Fabricated in 180-nm CMOS, the prototype consumes 41mW including LO buffers and output drivers. Measurement results demonstrate wideband operation, low sensitivity to LO drive level, and state-of-the-art suppression of undesired fundamental mixing products, making the design suitable for next-generation WLAN receivers operating in the 6-GHz band.