《基于fpga的数字波形发生器》论文.doc

摘要
系统基于FPGA设计,VHDL编程实现。系统集成于一片Xilinx公司的SpartanⅡ系列XC2S100-PQ208芯片上,核心技术是直接数字频率合成技术,其中包括固定分频器,正弦波合成器,三角波、矩形波、锯齿波发生器,波形选择模块,键盘控制模块,它们输出的8位数据通过D/A转换并经功率放大后即得所需波形,通过改变相位步进可调频率,通过改变D/A电阻网络的基准电压可调幅度。系统的频率范围宽,可从10Hz到10kHz之间等步进调节,最小步进10Hz,幅度和频率精度高。随着计算机和微电子技术在测量中的应用以及众多领域对波形信号的要求,任意波形发生器越来越成为测量领域内研究的焦点。目前国内外均采用了直接数字合成技术DDS(Direct Digital Synthesis)来实现任意波形发生器,直接数字合成技术采用全数字的合成方法,所产生的信号具有频率分辨率高、频率切换速度快、频率切换时相位连续、输出相位噪声低和可以产生任意波形等诸多优点。USB是应用在PC领域内的新型接口技术,作为外设的通用接口,具有传输速度快、支持热插拔、具有较强的纠错能力、具有自动探测设备的功能等特点。本文的研究工作为基于USB接口的任意波形发生器的研究。全面的分析任意波形发生器设计技术和USB接口设计技术,给出了基于USB接口、应用DDS技术的任意波形发生器的设计原理和实现方法。本论文首先介绍了任意波形发生器的发展概况,然后阐述了USB通信协议和DDS技术,最后给出了任意波形发生器的硬件和软件设计方法,采用FPGA实现了DDS功能,分析了模拟通道的设计,重点介绍了滤波器、幅值控制的设计。对USB驱动设计,固件编程做了相应的分析。
关键字:门阵列频率合成数模转换
ABSTRACT
The system is implemented by programmed with VHDL base on FPGA. the system whose basic technique is DDFS (Direct Digital Frequency Synthesis) is integrated into a Xilinx’s SpartanⅡXC2S100-PQ208 FPGA chip that consisted of a frequency divider, a sine wave synthesizer, a triangular wave, rectangular wave and sawtooth wave generator, a wave selecting module and a keyboard module. The 8-bit output data of the FPGA are converted by a D/AC and then amplified. By altering the phase increment, the frequency of the output wave can be changed. By altering the reference voltage of the D/AC resistances, the amplitude of the output wave can be adjusted. The system has a wide frequency range and is able to step evenly with the minimum of 10Hz. The frequency and the amplitude are in high accuracy. With the application puter and microelectronic technique in measuring and the demand of waveform signal in many fields, the measurement field focuses on the Arbitrary Waveform Generator(AWG). Currently Direct Digital Synthesis (DDS) is adopted in order to fulfill AWG in foreign and panies. The DDS technique adopts full-digital synthesis methods. The generated signals have advantage of high frequency resolutions, fast frequency switching, continuous phase whil