第1个回答 2011-03-10
一块DDS芯片中主要包括频率控制寄存器、高速相位累加器和正弦计算器三个部分(如Q2220)。频率控制寄存器可以串行或并行的方式装载并寄存用户输入的频率控制码;而相位累加器根据
dds
频率控制码在每个时钟周期内进行相位累加,得到一个相位值;正弦计算器则对该相位值计算数字化正弦波幅度(芯片一般通过查表得到)。DDS芯片输出的一般是数字化的正弦波,因此还需经过高速D/A转换器和低通滤波器才能得到一个可用的模拟频率信号。
另外,有些DDS芯片还具有调幅、调频和调相等调制功能及片内D/A变换器(如AD7008)。
DDS也是药物传递系统的意思。
DDS在化学里是一种良好的固化剂,全称为:4,4’ 二氨基二苯砜
FPGA(Field-Programmable Gate Array),即现场可编程门阵列,它是在PAL、GAL、CPLD等可编程器件的基础上进一步发展的产物。它是作为专用集成电路(ASIC)领域中的一种半定制电路而出现的,既解决了定制电路的不足,又克服了原有可编程器件门电路数有限的缺点。
EDA在通信行业(电信)里的另一个解释是企业数据架构,EDA给出了一个企业级的数据架构的总体视图,并按照电信企业的特征,进行了框架和层级的划分。 EDA是电子设计自动化(Electronic Design Automation)的缩写,在20世纪60年代中期从计算机辅助设计(CAD)、计算机辅助制造(CAM)、计算机辅助测试(CAT)和计算机辅助工程(CAE)的概念发展而来的。VHDL的英文全名是Very-High-Speed Integrated Circuit HardwareDescription Language,诞生于1982年。1987年底,VHDL被IEEE和美国国防部确认为标准硬件描述语言 。自IEEE公布了VHDL的标准版本,IEEE-1076(简称87版)之后,各EDA公司相继推出了自己的VHDL设计环境,或宣布自己的设计工具可以和VHDL接口
第2个回答 2011-03-11
Along with the development of modern electronic technology, digital signal generator used more widely discussed in this paper, A kind of DDS as the basic unit of digital move believe number generator design method of design USES direct digital frequency synthesis (DDS) technology, using the FPGA chip and D/A converter, implements A frequency phase of controllable sine signal generator
Direct digital frequency synthesis (DDS) technology is a new frequency synthesis technology, generated signal has a frequency resolution high frequency fast switching frequency when switching phase continuous output phase noise is low and can produce arbitrary waveform, and many other advantages.The field reprogrammable array FPGA is large-scale programmable device, it has high speed large scale programmable and have powerful EDA software design platform support characteristics.The realization of DDS relies on FPGA this high-speed high-performance digital devices, USES its characteristics, can according to need to be able to achieve different frequency signal output
This experiment on DDS principle and its output signal is analyzed with, make full use of FPGA chip, using VHDL language successfully write out the design program, and in Quartus2 software environment, to compile the program VHDL is simulated, and validate the design results.Through the design and circuit testing, the output waveform reached technical requirements, control the flexible performance is better, completed based on DDS digital move believe number generator design本回答被提问者采纳