一种基于FPGA的数字上变频实现方法

本文在上变频原理的基础上分析了不同的内插方法并对插值滤波器做了选择。介绍了CIC滤波器的基本组成原理,说明其结构简单、规整,没有乘法器,占用存储量小,适合工作在高采样率和插值比很大的场合。另外从时域和频域分析了CIC滤波器的本质,并讨论了其内部寄存器的最小位宽与溢出保护,实现了高效的CIC内插滤波器。结合FPGA集成性高、可靠性好、应用灵活等优点,进行了仿真、综合,验证了设计的正确性,最终达到了设计要求。

A Method based on FPGA in Digital Up Converter

Interpolation and decimation are common methods of sample rate conversion in DSP. Based on the theory of Digital Up Converter （DUC）,different methods of interpolation are analyzed to choose suitable interpolation fiher.The basic theory of the composition of Cascaded Iintegrator Comb（CIC） fiber is described to show that the structure of CIC filter is simple, neat and no multipliers,which makes it take smaller storage capacity and suitable to work in occasions where the sampling rate is high and interpolation is big. The nature of CIC filter in the time domain and frequency domain is analyzed and its smallest hit width of internal registers and overflow protection are discussed to achieve an efficient CIC interpolation filter. Combined with the high integration,high reliability and application flexibility of FPGA,the simulation and synthesis are done and prove the validity and veracity of the design. Finally,the design requirements are meeted.