The increasing demand for wireless communication products is translating into innovation in system architecture, as well as circuits design methodology and techniques. At the core of these approaches is high emphasis in finding the right integrated chip that provides small size, low cost, fewer off-chip components, better integration, and low operating voltage. To serve these needs, III-V semiconductors such as GaAs have been used successfully so far. However, the integration of highly complex digital circuits on GaAs is often prohibitive because of high cost, limited wafer size, processing complexities, and poor yield. The maturity, integration level, and low-cost aspects of Si technology make it attractive for this high-volume marketplace. Besides its superiority at intermediate frequencies, the recent advances in Si/SiGe heterostructure devices and circuits allows it to be competitive with GaAs at microwave and millimeter wave frequencies.