Abstract: A low-noise active down-conversion mixerwith a current-source switch stageis proposed. Large sinusoidal LO(Local Oscillator) signal driving is used to avoid the traditional RF port noise transferring by LO harmonics. An LC resonance tank structure is exploited to mitigate the high-frequency limitation by the tail parasitic capacitances charging and discharging behavior. Implemented in a 65nm CMOS process, the proposed mixer prototype operates at an RF dual-band of 5.2 GHz and provides a maximal conversion gain of 11.6dB andinput third-order intercept point (IIP3) of 5.5dBm. For 5.2 GHz LO, the dual side-band noise figure of 4.3/3.3dB is measured at fIF =10/200 MHz, respectively. The mixer core only consumes 8.4mW from a 1.2V supply voltage.