This thesis presents the design methodology and silicon implementation of a 0.13μm CMOS up-conversion mixer for wireless applications. The design approach is simulation based while maintaining the appropriate reference to the theory. The novelty of this work mainly consists in the implementation of the wide band digital phase shifter on the same chip with the analog mixer/multiplier cells. The design methodology allows a cost effective implementation of a fully integrated solution that requires 1.2x1.55mm of silicon and it can be used in any wireless device that transmits digitally modulated data. The following components were designed, simulated then integrated on chip: wideband digital phase shifter, two Gilbert cells for the I and Q paths, wideband active balun and biasing cells.