A SiGe micromixer for 2.4/5.2/5.7-GHz multiband WLAN applications is demonstrated for the first time. Our experimental results show that the input return loss |S11| is below -18 dB from DC to 20 GHz with voltage gains of 32, 26, and 25 dB at frequencies of 2.4, 5.2, and 5.7 GHz, respectively. The wideband matching characteristic makes the micromixer very suitable for multiband applications. Input P1dB = -14 dBm and IIP3 = -6 dBm. Port-to-port isolation is also quite satisfactory. In addition, the single-to-differential Input stage in the Gilbert micromixer eliminates the need for common-mode rejection.