This book focuses on the architecture and circuit design for cognitive radio receiver front-ends. The authors first provide a holistic explanation of RF circuits for cognitive radio systems. This is followed by an in-depth exploration of existing techniques that can be utilized by circuit designers. Coverage also includes novel circuit techniques and architectures that can be invaluable for designers for cognitive radio systems. Discusses in detail the circuit-level challenges that exist for cognitive radio systems; Provides readers with a holistic understanding of RF circuits for cognitive radio systems; Enables communications engineers and systems designers to design better cognitive radio architectures and communication protocols.