Research on the DDS´ CPLD Control to Generate Special Band Signal

Direct digital frequency synthesis (DDS) in often used in RF(Radio Frequency) systems, such as MRI(Magnetic Resource Imaging). This paper describes a DDS chip AD9854 ´s structure and its essential program by a CPLD chip XCldrldrldrldrldrXLldrldrR gives us material internal structure and how to program AD9854, and how to generate a radio frequency by AD9854 with CPLD´s control. The program code is written in VHDL, and all codes are simmulated through ModelSim SE 5.6d. At last, the paper gives conclusion that using CPLD control DDS chip to generate radio frequency is absolutely feasible.