A single sideband (SSB) up-conversion mixer with high sideband suppression (SBS) is presented on 65-nm CMOS technology. Utilizing a high impedance transmission line LO matching network and a 2-stage castle-wall polyphase filter (PPF), the SSB up-conversion mixer achieves high SBS. The measured conversion gain of the mixer is -20.3±1.5 dB from 15 to 31GHz via 3 dBm LO power. The SSB up-conversion mixer achieves broad SBS (>30 dBc) from RF frequency 13 to 23 GHz with the fractional bandwidth (FBW) of 55.5%. In addition, the SBS of the mixer is better than 55 dBc for RF frequencies from 18.5 to 20.2 GHz and IF frequencies from 2.8 to 5.7 GHz.