Designing Efficient Digital Up and Down Converters for Narrowband Systems

Abstract

Digital Up Converters (DUC) and Digital Down Converters (DDC) are key components of RF systems in communications, sensing, and imaging. This application note demonstrates how efficient DUC/DDC implementations can be created by leveraging Xilinx® DSP tools and IP portfolio for increased productivity and reduced development time. While previous application notes [Ref 1] have provided examples of DUC and DDC implementation in wideband communications systems, this document concentrates on narrowband systems and the building block components available to meet the particular requirements of such designs. Step-by-step guidance is provided on how to perform simulation of narrowband DUC/DDC systems in MATLAB®, how to map functions onto building blocks and IP cores for Xilinx® FPGAs in System Generator software, and how to verify the implementation against the simulation model. Two examples are provided: a multi-carrier GSM system (both DUC and DDC) and a multi-channel MRI receiver (DDC only). The examples provide a guide and template for implementation of customer-specific solutions and, in many cases, may be readily adapted to customers’ own application systems. Advantages and limitations of the approaches and methods employed are identified such that the reader can consider these in their own system context.