• Design of software defined down-conversion and up-conversion: an overview

      Zhang, Yue; Huang, Li-Ke; Maple, Carsten; Xuan, Qing (ZTE corporation, China, 2011-12)
      In recent years, much attention has been paid to software-defined radio (SDR) technologies for multimode wireless systems. SDR can be defined as a radio communication system that uses software to modulate and demodulate radio signals. This article describes concepts, theory, and design principles for SDR down-conversion and up-conversion. Design issues in SDR down-conversion are discussed, and two different architectures, super-heterodyne and direct-conversion, are proposed. Design issues in SDR up-conversion are also discussed, and trade-offs in the design of filters, mixers, NCO, DAC, and signal processing are highlighted.