电子工程设计EDA.doc

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1、电子工程设计EDA1EDA技术的基本概念EDA是电子设计自动化(ElectronicDesignAutomation)的缩写,是从CAD(计算机辅助设计)、CAM(计算机辅助制 造)、CAT(计算机辅助测试)和CAE(计算机辅助工程)的概念发展而来的。EDA技术是以计算机为工具,集数据库、图形学、图论与拓扑逻辑、计算数 学、优化理论等多学科最新理论于一体,是计算机信息技术、微电子技术、电路理论、信息分析与信号处理的结晶。2EDA技术的发展过程EDA技术的发展过程反映了近代电子产品设计技术的一段历史进程,大致分为3个时期。1)初级阶段:早期阶段即是CAD(ComputerAssistDesign

2、)阶段,大致在20世纪70年代,当时中小规模集成电路已经出现,传统的手工制图设计印刷电路板和集成电路的方法效率低、花费大、制造周期长。人们开始借助于计算机完成印制电路板一PCB设计,将产品设计过程中高重复性的繁杂劳动如布图布线工作用二维平面图形编辑与分析的CAD工具代替,主要功能是交互图形编辑,设计规则检查,解决晶体管级版图设计、PCB布局布线、门级电路模拟和测试。2)发展阶段:20世纪80年代是EDA技术的发展和完善阶段,即进入到 CAE(ComputerAssistEngineeringDesign)阶段。由于集成电路规模的逐步扩大和电子系统的日趋复杂,人们进一步开发设计 软件,将各个CA

3、D工具集成为系统,从而加强了电路功能设计和结构设计,该时期的EDA技术已经延伸到半导体芯片的设计,生产出可编程半导体芯片。3)成熟阶段:20世纪90年代以后微电子技术突飞猛进,一个芯片上可以集成几百万、几千万乃至上亿个晶体管,这给EDA技术提出了更高的要求,也 促进了EDA技术的大发展。各公司相继开发出了大规模的EDA软件系统,这时出现了以高级语言描述、系统级仿真和综合技术为特征的EDA技术。3EDA技术的特点EDA技术代表了当今电子设计技术的最新发展方向,它的基本特征是采用高级语言描述,即硬件描述语言 HDL(HardwareDescriptionLanguage),就是可以描述硬件电路的功

4、能。信号连接关系及定时关系的语言。它比电原理图更有效地 表示硬件电路的特性,同时具有系统仿真和综合能力,具体归纳为以下几点:1)现代化EDA技术大多采用“自顶向下(Top-Down)”的设计程序,从而确保设计方案整体的合理和优化,避免“自底向上(Bottom-up)”设计过程使局部优化,整体结构较差的缺陷。2)HDL给设计带来很多优点:语言公开可利用;语言描述范围宽广;使设计与工艺无关;可以系统编程和现场编程,使设计便于交流、保存、修改和重复使用,能够实现在线升级。3)自动化程度高,设计过程中随时可以进行各级的仿真、纠错和调试,使设计者能早期发现结构设计上的错误,避免设计工作的浪费,同时设计人

5、员可以抛开一些具体细节问题,从而把主要精力集中在系统的开发上,保证设计的高效率、低成本,且产品开发周期短、循环快。4)可以并行操作,现代EDA技术建立了并行工程框架结构的工作环境。从而保证和支持多人同时并行地进行电子系统的设计和开发。4EDA技术的作用EDA技术在电子工程设计中发挥着不可替代的作用,主要表现在以下几个方面:4.1验证电路设计方案的正确性设计方案确定之后,首先采用系统仿真或结构模拟的方法验证设计方案的可行性,这只要确定系统各个环节的传递函数(数学模型)便可实现。这种系统仿真 技术可推广应用于非电专业的系统设计,或某种新理论、新构思的设计方案。仿真之后对构成系统的各电路结构进行模拟

6、分析,以判断电路结构设计的正确性及性能 指标的可实现性。这种量化分析方法对于提高工程设计水平和产品质量,具有重要的指导意义。4.2电路特性的优化设计元器件的容差和工作环境温度将对电路的稳定性产生影响。传统的设计方法很难对这种影响进行全面的分析,也就很难实现整体的优化设计。EDA技术中的 温度分析和统计分析功能可以分析各种温度条件下的电路特性,便于确定最佳元件参数、最佳电路结构以及适当的系统稳定裕度,真正做到优化设计。4.3实现电路特性的模拟测试电子电路设计过程中,大量的工作是数据测试和特性分析。但是受测试手段和仪器精度所限,测试问题很多。采用EDA技术后,可以方便地实现全功能测试。5EDA技术

7、的软件目前EDA技术的软件很多,如EWB、PROTELL等。1)EWB(ElectronicsWorkbench)软件。EWB是基于PC平台的电子设计软件,由加拿大 InteractiveImageTechnologiesLtd.公司研制开发,该软件具有以下特点:集成化工具:一体化设计环境可将原理图编辑、 SPICE仿真和波形分析、仿真电路的在线修改、选用虚拟仪器、借助14种分析工具输出结果等操作在一个集成系统中完成。仿真器:交互式32位 SPICE强化支持自然方式的模拟、数字和数/模混合元件。自动插入信号转换界面,支持多级层次化元件的嵌套,对电路的大小和复杂没有限制。只有提供原理 图网络表和

8、输入信号,打开仿真开关就会在一定的时间内将仿真结果输出。原理图输入:鼠标点击一拖动界面,点一点自动连线。分层的工作环境,手工调整元器 件时自动重排线路,自动分配元器件的参考编号,对元器件尺寸大小没有限制。分析:虚拟测试设备能提供快捷、简单的分析。主要包括直流工作点、瞬态、交流 频率扫描、付立叶、噪声、失真度、参数扫描、零极点、传递函数、直流灵敏度、最差情况、蒙特卡洛法等14种分析工具,可以在线显示图形并具有很大的灵活 性。设计文件夹:同时储存所有的设计电路信息,包括电路结构、SHCE参数、所有使用模型的设置和拷贝。全部存放在一个设计文件中,便于设计数据共享以 及丢失或损坏的数据恢复。接口:标准

9、的SPICE网表,既可以输入其他CAD生成的SHCE网络连接表并行成原理图供EWB使用,也可以将原理图输出到 其他PCS工具中直接制作线路板。2)PROTEL软件。广泛应用的Protel99主要分为两大部分:用于电路原理图的设计原理图设计系统(AdvancedSchematic)和用于印刷电路板设计的印刷电路板设计系统(AdvancedPCB)。6EDA技术的发展趋势高层次设计技术是近几年来国际上在EDA技术领域研究、开发、应用的热门课题,并且发展非常迅速,成效异常显著。这一领域主要包括功能强大的硬件描 述语言、高层次综合技术、高层次模拟技术以及测试设计的综合技术等。相信随着科学技术水平的不断

10、进步,作为EDA发展方向的高层次自动化设计技术必将取得 更辉煌的成绩。Electronic engineering EDA1EDA Basic concepts of technologyEDA Electronic design automation (ElectronicDesignAutomation) Abbreviation of , From CAD ( computer aided design ) 、 CAM ( computer-aided ) 、 CAT ( cat ) CAE ( computer aided engineering ) Concepts of devel

11、opment. EDA technology is based on the computer as a tool , set, graph, graph theory and topology of the database logic, calculate the number of latest theory, optimization theory, and other disciplines in one , computer information technology, microelectronic technology, circuit theory, Crystalliza

12、tion of information analysis and signal processing. 2EDA Process technology developmentEDA Technology to reflect the development of the modern history of electronic product design process , Roughly divided into 3 A period. 1)Primary stage : That was in the early stages CAD(ComputerAssistDesign) Stag

13、e , 20 Century 70 , Small and medium scale integrated circuits have emerged at that time , Traditional methods of hand-drawing design of printed circuit board and IC is inefficient, costly and long manufacturing cycle. People began to use the computer to complete a printed circuit board PCB Design ,

14、 Product design process in a complex, highly repetitive work such as layout wiring work with two-dimensional graphics editing and analysis CAD Tools in place , Main feature is the interactive graphics editing , Design rule checking , Solve the transistor-level layout, PCB Layout wiring, gate-level c

15、ircuit simulation and testing. 2)Stages of development :20 Century 80 Age to EDA Stages of technology development and improvement of , He entered to CAE(ComputerAssistEngineeringDesign) Stage. Scale gradually expanded due to integrated circuits and electronic systems of increasing complexity , furth

16、er development and design software , various CAD Tools into your system , Thus strengthened the circuit design and structure design , The period of EDA Technology has extended to semiconductor chip designs , Production of programmable semiconductor chips. 3)Mature stage :20 Century 90 Microelectroni

17、cs technology is advancing by leaps in the future , Can be integrated on a single chip, millions of even billions of transistors , EDA Higher demands on technology , Promotes EDA technology in development. The company developed a mass of EDA software system , appears in the advanced language descrip

18、tion, simulation and characteristics of comprehensive technology for system-level EDA technology. 3EDA Technical characteristics ofEDA Technology represents the latest development of todays electronic design technology , Its basic feature is the use of advanced linguistic description , Hardware desc

19、ription language HDL(HardwareDescriptionLanguage), Is the functionality of hardware circuit can be described. Relationship between timing and signal connection between the languages. It more effectively than the electrical schematic diagram represents the hardware characteristics of the circuit , at

20、 the same time with system simulation and synthesis capabilities , grouped into the following several points:1)Modern EDA Technology they use “ Top-down (Top-Down)” Design program , So as to ensure that the overall design scheme optimization of reasonable and , Avoid “ From the bottom up (Bottom-up)

21、” Design process so that local optimization , Poor overall structure of defects. 2) HDL design brings many advantages : language available to the public ; Describes the wide range of language ; Design and technology-independent ; System programming and coding , Make design easy to share, save, modif

22、y, and reuse , To upgrade online. 3)High degree of automation , You can at any time in the design process for various levels of simulation, error checking and debugging , Early detection structure enables designers to design errors , Avoid waste of design work , While designers can set aside some sp

23、ecific details , Thus focused mainly on the system development , Ensure the design of high efficiency and low cost , And short product development cycles, cycle faster. 4)Parallel operation , Modern EDA Technology to build a work environment of concurrent engineering framework. To guarantee and supp

24、ort people at the same time in parallel to the electronic systems design and development. 4EDA Role of technologyEDA Technology plays an irreplaceable role in electronic engineering , Mainly in the following aspects:4.1Verify the correctness of the circuit designDesign after the , First system emula

25、tion or simulation method to verify the feasibility of design , As long as determines all aspects of the system transfer function ( Mathematical models ) Will be able to achieve. This kind of system simulation technology application in non-professional system design , or design of a new theory, new

26、ideas. Constituted after the simulation system of circuit simulation and analysis , to determine the correctness of the circuit design and performance indicators can be achieved. This quantitative analysis methods for raising the level of design and product quality , is of great significance. 4.2Opt

27、imization design of circuit characteristicsComponents of the tolerance and working temperature will have an impact on the stability of the circuit. Traditional design methods are difficult to conduct a comprehensive analysis of this effect , is hard to achieve the overall optimization. EDA technolog

28、y in the thermal analysis and statistical analysis to analysis of circuit characteristics under various temperature conditions , easy to determine the best best circuit component parameters, structures as well as adequate stability margins , truly optimized design. 4.3Implement circuit simulation of

29、 testIn electronic circuit design process , Lots of work is the testing and analysis of data. But subject to the limited precision of testing means and instruments , test many issues. Using EDA technology , you can easily implement a fully functional test. 5EDA Technology softwareNow EDA Technology

30、software a lot , EWB 、 PROTELL , And so on. 1) EWB (ElectronicsWorkbench) software. EWB is based on PC platform of electronic design software , Canada InteractiveImageTechnologiesLtd. Research and development company , The software has the following features : Integrated tools : Schematic diagram ca

31、n be edited, integrated design environment SPICE Online simulation waveform analysis, simulation and circuit modification, selection of virtual instruments, with 14 Kinds of analysis tools to output results in an integrated system completed. Emulator : interactive 32 -bit SPICE enhanced support for

32、analog, digital, and number of natural / Mixed components. Automatic insertion of signals interface , supports multiple levels of nesting of components , there are no restrictions on the circuit and the size of the complex. Only the principle of providing network table and input signal , switch will

33、 open simulation output simulation results within a certain time. schematic capture : click on the mouse dragging interface , automatic lines. Tiered environments , manually adjust the time automatically reroute the line , automatic distribution of components of the reference number , no restriction

34、s on size of components. analysis : virtual test equipment can provide fast, simple analysis. Includes DC operating point, transient, AC frequency scan, fuliye, noise, distortion, parameter scanning, zero-pole, DC transfer function, sensitivity, worst case, Monte Carlo and other 14 kinds of analysis

35、 tools , can display graphics online, and have a lot of flexibility . design folder : while storing all circuit design information , including circuit structure,SHCE parameter, all settings, and copy using the model. All in one design files , easy to design data sharing and data recovery of lost or

36、damaged. interface : standard SPICE netlist , you can enter other CAD SHCE Schematic diagram of parallel to the table for a network connection EWB , Schematic diagram can also be output to PCS Making printed circuit boards directly in the tool. 2) PROTEL software. Widely Protel99 is divided into two

37、 parts : design schematic design system for circuit schematic diagram (AdvancedSchematic) and printed circuit board design system for printed circuit board design ( AdvancedPCB)。 6EDA Technical development trendHigh level design are in recent years on the international EDA Hot topics in technology r

38、esearch, development, application , And development very quickly , Abnormal results significantly. This area includes a powerful hardware description language in high level simulation technology, high level synthesis technology, design and test of integrated technology. Believe that as the level of science and technology progress , as EDA development direction of a high-level design automation technology will surely achieve even greater results.