Proposed in this paper is a novel high-linearity double-balanced mixer for wireless radio frequency ( R F)systems,which outputs signals without R F signal-related second-order nonlinear term.In this mixer based on a novelmultiplier structure,R F signals are sent to the source and the drain of two symmetrical MOS ( Metal Oxide Semiconductor)transistors in the linear region,and local oscillator ( LO) signals are sent to the grid.Thus,the doublebalancedmixing or multiplying of R F and LO signals are implemented with low complexity. Moreover,the differentialpush-pull amplifier and the source follower are used as the output buffer interfaces,thus improving the isolation betweenthe mixer and the outside circuits,the power gain and the output matching ability.The proposed mixer is fabricatedby 0.18μm CMOS process and is used as a multiplier in ultra-wide band,with an input 1dB compression pointof 2.9 dBm,a third-order intermodulation of 16 dBm and a total power consumption of 25 mW. Test results demonstratethat the proposed mixer is of good performance and meets the requirements of high-performance and high-speedultrawideband wireless communication systems.