Designand Realization Of Digital Baseband Module Based On DDS

Signal generator is widely used, with the unceasing progress of science and technology, the main trend of the development of the industry is to develop a higher performance signal generator to meet the wide needs of radar, communications, automation and other fields. And direct digital frequency synthesis technology which has high accuracy, high stability and other advantages is one of the core technology of signal generator, but also one of the research point of the major companies. In this thesis, we design and implement digital baseband signal generator module based on direct digital frequency synthesis technology.In this paper, firstly, the basic principles and theoretical basis of direct digital frequency synthesis technology arestudied. Then, four kinds of digital baseband module design scheme are given. They are the FPGA plus DAC scheme, the controller and DDS chip scheme, and the selection scheme of the controller include MCU, DSP and FPGA. Through the analysis of the characteristics of the above four schemes, one of the most suitable scheme is chosen for the hardware design, and the module design is divided into five functional circuit modules according to the function of the module.Secondly,this paper will demonstrate the overall design scheme of the digital baseband module based on DDS and the hardware design workflow. The design principle of each unit circuit and its peripheral circuit is analyzed, including the DDS peripheral configuration and filter circuit design, clock unit circuit design, FPGA unit circuit design, power unit circuit design.In this paper, the signal integrity in the design of PC B is introduced in detail. andthe PCB design plan is completed according to the basic requirement of signal integrity,Secondly,implementthespecific PCB circuit design according to the plan, including laminated design, placement and layout of PCB.At last, the reliability of the module is designed from power supplydesign, PCB grounding design, hardware design and electromagnetic compatibility design. The PCB design about high frequency and high speed circuit is a complicated process. Many factors affect each other, and all kinds of these factors can affect the function of the module. For meeting the functional performance and reliability requirements of PCB, it need to comply with PCB design specifications when design, the design priority also need to weigh the pros and cons to seek optimal design.At last,as the practical verification, the module design of the subject satisfy the functional requirements of the performance indicators, and it worksstablely and reliablely.