基于CORDIC算法的DDS研究及FPGA实现

发布时间：2018-02-08 22:41

本文关键词： 直接数字频率合成 CORDIC算法数字锁相放大器 FPGA　出处：《东北大学》2015年硕士论文　论文类型：学位论文

【摘要】：随着数字电路和微电子技术的发展,信号发生器在雷达、通信、导航、电子对抗和仪器仪表等领域的应用十分广泛。人们实际应用中在分辨率、频谱纯度、频率范围等方面对信号发生器的要求越来越高,基于直接数字频率合成(Direct Digital Synthesis,简称DDS)的高精度信号发生器解决了以往采用的频率合成方法设计的信号发生器在技术上存在诸多问题,因此被很多人称为电子系统的"心脏"。本文采用EDA(Electronic Design Automation)技术设计了 DDS信号发生器。首先概述了 DDS技术发展现状和工作原理,坐标旋转数字计算机(coordinate rotation digital computer,CORDIC)算法的原理和结构,以及锁相放大器和数字积分电路的原理。然后着重介绍了 DDS的设计,根据上述相关理论,本论文使用CORDIC算法代替传统的ROM查找表结构,并使用锁相放大器进行信号幅度检测,将CORDIC模块产生的正余弦波转化为方波和三角波,并从节省硬件资源的角度对锁相放大器进行了改进。系统设计的硬件平台采用的是Altera公司FPGA开发板DE2-115。首先在Matlab/Simulink中完成模型搭建,进行仿真验证。在QuartusII软件中使用的Verilog HDL语言进行DDS的设计和仿真,最终在QuartusII环境中生成符号文件,从而实现设计模块在FPGA上的实体化。最后,利用Modelsim工具仿真验证了 DDS的系统功能,并且对比了改进前后两种方法设计的DDS系统的硬件开销情况。测试结果表明:第一,使用CORDIC算法实现的DDS信号发生器各个模块功能仿真和输出波形,验证了模块功能的正确性;第二,采用CORDIC算法更能节省硬件资源,改进后的设计能进一步节省硬件资源;最后,本论文对以后进一步的研究与开发提供了实验依据。
[Abstract]:With the development of digital circuit and microelectronic technology, signal generator is widely used in radar, communication, navigation, electronic countermeasure and instrument. The frequency range and other aspects of the signal generator are becoming more and more demanding. The high precision signal generator based on Direct Digital Synthesis (DDS) has solved many technical problems of the signal generator which was designed by the frequency synthesis method in the past. Therefore, many people call the "heart" of electronic system. This paper uses EDA(Electronic Design Automation technology to design DDS signal generator. Firstly, the development status and working principle of DDS technology are summarized. The principle and structure of coordinate rotation digital computer Cordic algorithm, as well as the principle of phase-locked amplifier and digital integral circuit are introduced. In this paper, the CORDIC algorithm is used to replace the traditional ROM lookup table structure, and the phase-locked amplifier is used to detect the amplitude of the signal. The sine cosine wave generated by the CORDIC module is converted into square wave and triangle wave. The hardware platform of the system is Altera FPGA development board DE2-115. firstly, the model is built in Matlab/Simulink. The Verilog HDL language used in QuartusII software is used to design and simulate DDS. Finally, the symbol file is generated in the QuartusII environment, which realizes the materialization of the design module on FPGA. The system function of DDS is verified by Modelsim simulation, and the hardware overhead of DDS system designed by two methods before and after the improvement is compared. The test results show that: first, The function simulation and output waveform of each module of DDS signal generator realized by CORDIC algorithm verify the correctness of the module function. Secondly, the use of CORDIC algorithm can save more hardware resources, and the improved design can further save hardware resources. This paper provides experimental basis for further research and development.
【学位授予单位】：东北大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN741

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