Modern system-on-chip designs are increasingly mixed-signal designs that require efficient systematic design methodologies and supporting computer-aided design (CAD) tools to manage the design complexity in the available design time, that is ever decreasing due to tightening time-to-market constraints. The purpose of this work is to provide an overview of research results that have been achieved as part of the Low-Power Initiative of the European Union, in the field of analog, RF and mixed-signal design methodologies and CAD tools. It is a representative sampling of the state-of-the art in this area, with special focus on low-power design methodologies and tools for analog and RF circuits and architectures. Concrete designs, mainly for telecommunication applications, such as low-noise amplifiers, oscillators, filters, but also complete transceiver front-ends, are discussed and analyzed in a methodological way, and their modeling and simulation, both at the circuit level and at the architectural level, are treated. In this way, the eleven contributions of this book combine in a unique way designs with methodologies and CAD that should be interesting to designers and CAD developers, both in industry and academia.