A low-voltage quadrature up-conversion CMOS mixer for 5-GHz wireless communication applications is designed with a TSMC 0.18-µm process. The fold-switching technique is used to implement the low-voltage double balanced quadrature mixer. A miniature lumped-element microwave broadband rat-race hybrid and RLC shift network are used for the local oscillator and the intermediate frequency port design, respectively. The measured results demonstrate that the mixer can reach a high conversion gain, a low noise figure (NF), and a high linearity. The mixer exhibits improvement in noise, conversion gain, and image rejection. The mixer shows a conversion gain of 16 dB, a noise figure of 12.8 dB, an image rejection of 45 dB, while dissipating 15.5 mW for an operating voltage at 1 V.