A CMOS low-voltage downconversion mixer is presented. With 1.69-GHz local oscillator signal input and 1.63-GHz RF signal input, measurement results show that the conversion gain is 6.631 dB, input-referred third-order intercept point is 1.51 dBm, single-sideband noise figure is 21.43 dB with a 1.8-V supply voltage. The mixer’s noise and linearity analysis, layout technique to maximize RF performance and minimize noise performance are also presented in this paper. Index Terms—CMOS analog integrated circuits, low-voltage circuit,mixers, noise and linearity analysis.