Book excerpt: Communication devices such as smart phones, GPS systems, and Bluetooth, are now part of our daily lives more than ever before. As our communication equipment becomes more sophisticated, so do the radios and other hardware required to enable that technology. Common radio architectures are required to make this technology work seamlessly. This resource describes practical aspects of radio frequency communications systems design, bridging the gap between system-level design considerations and circuit-level design specifications. Industry experts not only provide detailed calculations and theory to determine block level specifications, but also discuss basic theory and operational concepts. This resource also includes extensive, up-to-date application examples.