This book is written for academic and professional researchers designing communication systems for pervasive and low power applications. There is an introduction to wireless sensor networks, but the main emphasis of the book is on design techniques for low power, highly integrated transceivers. Instead of presenting a single design perspective, this book presents the design philosophies from three diverse research groups, providing three completely different strategies for achieving similar goals. The design of RF transceiver circuits and architectures is historically (and notoriously) heuristic. By presenting diverse perspectives on transceiver design, this book prepares the reader for the countless design decisions they will be making in their own designs. The book includes invited chapters by leading research experts.