基于DDR3系统互联的信号完整性设计

针对DDR3系统互联中信号完整性和时序等问题,以某自研的自主可控计算设备为背景,详细描述了龙芯3A处理器和四片DDR3内存颗粒芯片互联的仿真分析和优化设计方案.分析了IBIS模型的结构和数据信息,介绍了一种快速验证IBIS模型准确性的方案.仿真分析了一种DDR3差分时钟电路共模噪声的控制方法.利用前仿真和后仿真,分析验证了多片DDR3内存颗粒芯片在Fly-By拓扑结构下的时序和信号质量.仿真结果达到了预期目标.     

龙芯3A处理器封装的散热设计

随着处理器的性能越来越高,处理器的功耗和温度也随之攀升,这就对处理器的封装提出了更高的要求。本文针对龙芯3A高性能处理器对封装的散热问题,根据成熟的工艺水平选择了FC-BGA封装形式,并对散热和外加散热措施的方法进行了分析和研究。实验模拟结果表明,FC-BGA的封装形式完全能满足龙芯3A处理器对封装散热的要求。     

基于动态目标阻抗的DDR3电源完整性仿真

DDR3存储器已经成为目前服务器和计算机系统的主流应用,虽然DDR3采用双参考电压、片上校准引擎、动态ODT、fly by拓扑以及write leveling等技术在一定程度上提高了信号完整性,但高数据率DDR3的设计实现仍然比较困难。由于DDR3总线属于高速并行总线,同步开关噪声与电源本身的噪声耦合在一起,共同影响数据信号的质量。考虑到芯片实际工作电流并非恒定不变,而是一种动态变化的频率相关源,提出了一种新的基于目标阻抗与动态目标阻抗的混合仿真与设计流程,在前仿真阶段采用恒定目标阻抗,在后仿真阶段采用动态目标阻抗为设计目标,仿真结果证实了该方法的有效性,实现了设计优化速度与精度的权衡折衷。     

TO-252封装电磁仿真分析

随着工艺尺寸的缩小和工作频率提高,表面贴片式封装技术中的PCB板和键合线都可能对电路的电气特性产生影响,因此有必要对这种封装技术进行信号完整性的分析。文章介绍了一种表面贴片封装TO-252,采用3D电磁仿真软件HFSS进行建模,分析仿真PCB板材、厚度和键合线的长度、拱高、根数及键合线间的距离对封装设计中信号传输的影响,为实物封装设计起指导作用。     

DDR3系统混合建模与协同仿真

DDR3存储器已经成为目前服务器和计算机系统的主流应用,虽然DDR3采用双参考电压、片上校准引擎、动态ODT、fly-by拓扑以及write-leveling等技术在一定程度上提高了信号完整性,但设计实现高数据率仍然比较困难.针对某自研处理器及服务器主板设计,采用混合建模方法,建立了由芯片I/O、封装、PCB、过孔、连接器和DIMM条组成的DDR3的全通道信号完整性仿真平台,通过频域仿真,比较通道中各种无源组件引入的插损和回损,通过时域仿真,分析各组件对接收眼图的不同影响程度,实现Chip,Package,PCB的协同仿真与设计优化,达到了预期指标.     

DDR3时序分析与设计

DDR3存储器已经成为目前服务器和计算机系统的主流应用,虽然DDR3采用双参考电压片上校准引擎、动态ODT、fly-by拓扑以及write-leveling等技术在一定程度上提高了信号完整性,但其时序的分析与设计实现仍然比较困难。针对某自研处理器及服务器主板设计,简要介绍了DDR3源同步信号传输的基本原理,使用时域信号仿真工具,量化分析了DDR3系统通道中影响时序的主要因素,并对DDR3的写操作时序进行了分析与裕量计算。仿真结果表明,信号占空比失真程度随着信号ODT值的改变和同时开关的I/O数目增加加剧了3%～5%,而串扰引入的时序偏斜可达218ps。     

嵌入式3G无线视频监控系统硬件设计与信号完整性仿真

提出了一种基于DaVinci平台的嵌入式3G无线视频监控系统的解决方案。该方案充分利用WCDMA网络的高带宽,可进行两路视频的同步监控。对系统的硬件设计进行了深入的探讨,设计了各个功能模块。应用Hyperlynx软件与IBIS模型对硬件PCB设计进行了仿真分析,有效地解决了系统DDR2接口电路中出现的反射、串扰等信号完整性（SI）方面的问题,充分保证了高速PCB设计的质量和速度。相比传统的有线视频监控,该方案更加灵活,使用范围更加广泛。     

基于龙芯2F处理器的CPCI主板设计

采用龙芯2F处理器设计实现了一款CPCI总线形式主板,介绍了主板关键模块的设计方案,对主板PCB设计中DDR2(double date rate 2)接口总线等关键信号的信号完整性以及电源完整性问题进行了分析,根据信号完整性经验法则对主板中的关键高速总线信号进行了优化设计,给出了设计完成后相关的实际波形效果图,验证了设...     

基于信号与电源完整性的有效分析优化2.5D-3D的设计

HBM(高带宽内存)存储系统与传统的DRAM接口相比,具有高速率和低功耗特性。在2.5D/3D的设计中,随着HBM速率的提高,对信号与电源完整性的设计的考量越来越重要,如何通过有效的仿真指导产品的设计是一个挑战。首先从信号完整性的角度讨论了设计的考量点,其次从电源完整性的角度讨论电源噪声在高速传输信号中的影响,并提出了如何仿真与预测大量同步开关噪声等电源噪声对眼图的影响,最后基于芯片的测试结果对比仿真,给出结论。     

基于FPGA的DDR3协议解析逻辑设计

针对采用DDR3接口来设计的新一代闪存固态盘（SSD）需要完成与内存控制器进行通信与交互的特点,提出了基于现场可编程门阵列（FPGA）的DDR3协议解析逻辑方案。首先,介绍了DDR3内存工作原理,理解内存控制器对存储设备的控制机制;然后,设计了接口协议解析逻辑的总体架构,采用FPGA实现并对其中的各个关键技术点,包括时钟、写平衡、延迟控制、接口同步控制等进行详细阐述;最后,通过modelsim仿真并进行板级验证,证明了该设计的正确性和可行性。在性能方面,通过单次读写、连续读写和混合读写三种模式下的数据读写测试,取得了最高77.81%的DDR3接口带宽利用率,在实际的SSD开发过程中能够有效提高系统的访问性能。     

军用计算机信号完整性分析与设计

随着高性能军用计算机的广泛运用,对其进行信号完整性设计的需求日益迫切。为提高军用计算机的信号完整性设计水平,文章从高速信号PCB设计、电缆和连接器三个方面对军用计算机信号完整性设计进行了分析。通过PCB板材及叠层设计、差分线设计、阻抗匹配设计、高品质电缆以及高速差分连接器等方面改善军用计算机高速信号质量,提高信号完整性,并且对这些改进的效果进行了测试验证。     

FPGA与DDR2 SDRAM互联的信号完整性分析

论述了Virtex-5和DDR2?SDRAM在互联中的信号完整性问题,利用前仿和后仿的措施分析和验证了它们在不同互联拓扑结构下的信号完整性。通过原型机的测试,验证了该理论在高速电路设计中的应用有效性。     

基于Web3D 的灯饰协同设计定制系统

论文分析了目前传统的灯饰设计所存在的不足,提出了客户与设计师协同 设计的可行方案,详细介绍了基于Web3D 的灯饰协同设计关键技术,包括灯饰模型交互设 计和同步互斥技术,开发出了一个以客户为主,以设计师为辅并基于Web3D 技术的网上协 同设计系统,并通过实验验证了系统的可行性。     

DMS2015-33: Generative interface structure design for supporting existing objects

Increasing availability of high quality 3D printing devices and services now enable ordinary people to create, edit and repair products for their custom needs. However, an effective use of current 3D modeling and design software is still a challenge for most novice users. In this work, we introduce a new computational method to automatically generate an organic interface structure that allows existing objects to be statically supported within a prescribed physical environment. Taking the digital model of the environment and a set of points that the generated structure should touch as an input, our biologically inspired growth algorithm automatically produces a support structure that when physically fabricated helps keep the target object in the desired position and orientation. The proposed growth algorithm uses an attractor based form generation process based on the space colonization algorithm and introduces a novel target attractor concept. Moreover, obstacle avoidance, symmetrical growth, smoothing and sketch modification techniques have been developed to adapt the nature inspired growth algorithm into a design tool that is interactive with the design space. We present the details of our technique and illustrate its use on a collection of examples from different categories.     

A system for desktop conceptual 3D design

In the traditional design process for a 3D environment, people usually depict a rough prototype to verify their ideas, and iteratively modify its configuration until they are satisfied with the general layout. In this activity, one of the main operations is the rearrangement of single and composite parts of a scene. With current desktop virtual reality (VR) systems, the selection and manipulation of arbitrary objects in 3D is still difficult. In this work, we present new and efficient techniques that allow even novice users to perform meaningful rearrangement tasks with traditional input devices. The results of our work show that the presented techniques can be mastered quickly and enable users to perform complex tasks on composite objects. Moreover, the system is easy to learn, supports creativity, and is fun to use.     

The design and realization of CoViD: a system for collaborative virtual 3D design

Many important decisions in the design process are made during fairly early on, after designers have presented initial concepts. In many domains, these concepts are already realized as 3D digital models. Then, in a meeting, the stakeholders for the project get together and evaluate these potential solutions. Frequently, the participants in this meeting want to interactively modify the proposed 3D designs to explore the design space better. Today’s systems and tools do not support this, as computer systems typically support only a single user and computer-aided design tools require significant training. This paper presents the design of a new system to facilitate a collaborative 3D design process. First, we discuss a set of guidelines which have been introduced by others and that are relevant to collaborative 3D design systems. Then, we introduce the new system, which consists of two main parts. The first part is an easy-to-use conceptual 3D design tool that can be used productively even by naive users. The tool provides novel interaction techniques that support important properties of conceptual design. The user interface is non-obtrusive, easy-to-learn, and supports rapid creation and modification of 3D models. The second part is a novel infrastructure for collaborative work, which offers an interactive table and several large interactive displays in a semi-immersive setup. It is designed to support multiple users working together. This infrastructure also includes novel pointing devices that work both as a stylus and a remote pointing device. The combination of the (modified) design tool with the collaborative infrastructure forms a new platform for collaborative virtual 3D design. Then, we present an evaluation of the system against the guidelines for collaborative 3D design. Finally, we present results of a preliminary user study, which asked naive users to collaborate in a 3D design task on the new system.     

多种哈希算法的可重构硬件架构设计

针对现有的哈希算法硬件架构仅实现少量几种算法的问题,设计了一种可实现SM3,MD5,SHA-1以及SHA-2系列共7种哈希算法的可重构IP,以满足同一系统对安全性可选择的需求。通过分析各哈希算法及其运算逻辑的相似性,该设计最大化地重用加法器和寄存器,极大地减少了总的实现面积。此外,该设计灵活可配,可以对内存直接存取。以Altera的Stratix II为FPGA目标器件,其最高频率可达100 MHz,总面积较现有设计减少26.7%以上,且各算法单位面积吞吐率均优于现有设计。