There are continuous efforts focussed on improving road traffic safety worldwide. Numerous vehicle safety features such as driver assistance systems have been invented. Many driver assistance features rely on radar-based sensors, but are highly-priced. Realization of low-cost radar front-end circuits would enable their implementation in less expensive economy cars, considerably contributing to traffic safety. Cost reduction requires high-level integration of the microwave front-end circuitry, specifically analog and digital circuit blocks co-located on a single chip. The book presents the design, implementation, and characterization of microwave receiver circuits in CMOS and SiGe bipolar technologies. The applicability of a standard digital 0.13 ?m CMOS technology for realization of a 24 GHz narrow-band radar front-end sensor is investigated. The presented circuits are suitable for automotive, industrial and consumer applications, as e.g. lane-change assistant, door openers or alarms.