mixed signal Transceiver

www.rfdesign.com February 2001 I today’s world of miniaturization, there is everincreasing industry pressure to reduce the cost of communication chips. This pressure has driven designers to develop transceivers with higher levels of integration1. Achieving the goal of maximum integration between the antenna and data output is not as trivial as replacing external components with on-chip components. Instead it requires a complete overhaul of the front-end design. Traditional radio designs that use excessive bills of materials are seen as less of a solution today where power, size and cost is critical. This has resulted in new radio architectures2-9 with fewer off-chip components. Over the past few years, communication systems have been making the transition from analog to digital modulation schemes. Digital modulation provides greater information capacity, higher security, and better quality of communication than analog modulation10, 11. In order to improve the modulation and spectral efficiencies, most digital signals are single side band with suppressed carrier. Over the years many architectures such as the filter method, phase shift method/Hartley architecture and Weaver architecture have evolved to achieve single side-band signals in transmitters10. In receivers, these architectures are used to achieve image rejection. Among these architectures, the Weaver and Hartley topologies10 are more suitable for integration. This article will provide an overview of recent advancements in receiver and transmitter architectures. It will discuss the system requirements that lead to the selection of a receiver and various topologies will be described. Transmitter requirements and different architectures will also be examined.