The present work is about the synthesis and design of a passive mixer in CMOS technology with carrier feed-through cancellation and output power modulation, which satisfies the demands established by Bluetooth, Ultra Wideband (UWB) and Medical Implant Communication Service (MICS). The simulation in Mentor Graphicsr ICstudio 2008:2b of the harmonic mixer for the Bluetooth and UWB standards with the UMC 0:18µm Mixed Mode and RF CMOS technology have been carried out. Furthermore, was designed and fabricated a passive mixer in a double poly three metal layers 0:5µm CMOS technology from MOSIS foundry for MICS standard. For the proposed designs for the UMC 0:18µm technology we have two designs, the first is single-ended and second is differential both proposals have identical performance in Gc with -6:05dB, IIP3 of 15:5dBm and a variation of the conduction angle from 40% to 7%. However, the differential mixer has an NF of 9:73dB which is superior compared to the NF of 7:7dB of the single-ended mixer; but the principal advantage of the differential mixer is that it removes all the harmonics of fLO and increases the dynamic range.