使用Verilog实现基于FPGA的SDRAM控制器

介绍了SDRAM的特点和工作原理，提出了一种基于FPGA的SDRAM控制器的设计方法，使用该方法实现的控制器可非常方便地对SDRAM进行控制。     

一种适用于MCU的SDRAM控制器的实现方法

介绍了同步动态存储器SDRAM的特点、操作原理，提出了一种对于MCU等微控制器有着友好接口的SDRAM控制器的实现方法，使得不带SDRAM控制器的微处理器可以方便地实现对于SDRAM的控制。     

基于FPGA的DDR SDRAM控制器在高速数据采集系统中的应用

实现数据的高速大容量存储是数据采集系统中的一项关键技术。本设计采用Altera公司Cyclone系列的FPGA完成了对DDR SDRAM的控制，以状态机来描述对DDR SDRAM的各种时序操作，设计了DDR SDRAM的数据与命令接口。用控制核来简化对DDR SDRAM的操作，并采用自顶至下模块化的设计方法，将控制核嵌入到整个数据采集系统的控制模块中，完成了数据的高速采集、存储及上传。使用开发软件QuartusⅡ中内嵌的逻辑分析仪Signal TapⅡ对控制器的工作流程进行了验证和调试。最终采集到的数据波形表明，完成了对DDR SDRAM的突发读写操作，达到了预期设计的目标。     

SDRAM控制器在数据采集中的应用

介绍了SDRAM的结构和控制时序特点。阐明基于FPGA的SDRAM控制器在多通道数据采集中的关键技术。给出SDRAM的控制命令以及多通路数据采集中的FPGA和SDRAM接口设计, 并且引入仲裁机制和状态机,发挥可编程逻辑器件的速度灵活及高集成度的特点,实现了快速高效地控制SDRAM完成大容量数据的存储。     

SDRAM控制器简易化设计

SDRAM存储芯片拥有快速读写的性能,可以应用以回波模拟系统作为数据高速缓存器。SDRAM芯片是由SDRAM控制器控制的,SDRAM控制器有严格的控制时序和工作状态,可以使用有限状态机理论和VerilogHDL语言对FPGA进行模块化开发设计。笔者基于FPGA给出了一种SDRAM控制器简易化设计方法,实验结果表明该方法简化了SDRAM控制器的设计。     

基于FPGA的SDRAM控制器设计与实现

针对SDRAM(Synchronous Dynamic Random Access Memory)在缓存图像数据时时序的控制比较复杂的问题,在研究SDRAM的特点和原理的基础上,提出了一种基于现场可编程逻辑器件FPGA(Field Programmable Gate Array)为核心的SDRAM控制器的设计方案。采用分模块的思想,把SDRAM的控制分成不同的功能模块,各模块之间通过信号状态线相互关联,并且相关模块利用状态机来控制整个时序的过程。另外,为了提高SDRAM的缓存速度,选择了SDRAM工作在页突发操作模式下,使SDRAM的读写速度有了大幅的提升。整个控制系统经过仿真和在线逻辑分析仪验证表明:控制器能准确地对SDRAM进行读写控制,稳定可靠,可应用于不同的高速缓存系统。     

用于多通道数据传输的SDRAM控制器设计与实现

介绍了SDRAM的结构和控制时序特点。阐明了SDRAM控制器在多通道数据传输中的电路对齐应用,并针对传输过程中各通道产生的数据延时提出了一种可行性的解决方案。最后根据SDRAM的基本控制命令,结合实际系统需要以及多通路数据采集中的FPGA和SDRAM接口设计要求,设计完成了一款高速、灵活的SDRAM控制器,并且为了便于后期调试,加入了SDRAM自检模式。仿真顺利通过并在硬件上调试成功。     

基于EPM1240的SDRAM控制器的设计

SDRAM的读写逻辑复杂,最高时钟频率达100 MHz以上,普通单片机无法实现复杂的SDRAM控制操作。复杂可编程逻辑器件CPLD具有编程方便,集成度高,速度快,价格低等优点。因此选用CPLD设计SDRAM接口控制模块,简化主机对SDRAM的读写控制。通过设计基于CPLD的SDRAM控制器接口,可以在STM系列、ARM系列、STC系列等单片机和DSP等微处理器的外部连接SDRAM,增加系统的存储空间。     

基于CPLD的SDRAM控制器

高速数据采集卡设计中需要大容量的存储单元,静态存储器无法满足容量要求,故选用同步动态存储器(SI)RAM)为该数据采集系统的存储单元。通过VIIDL语言描述电路,设计了基于CPL,D的SDRAM控制器,从而简化了主机对SDRAM的读写及其相关操作。SDRAM控制器设计采用自顶向下模块化的设计方法,共分为四个模块：SDRAM控制器顶层模块、控制接口模块、命令模块和数据通路模块,SDRAM控制器顶层模块初始化并把其余三个模块有机地结合起来。测试结果证明设计的SDRAM控制器成功地实现了对SDRAM的读写操作,地址、数据、控制信号时序匹配,满足了系统设计要求。     

SDRAM控制器的VHDL实现

本文介绍了SDRAM的控制时序特点,并介绍了采用VHDL语言的状态机实现SDRAM控制器的关键技术。     

Cost-effective test solutions for smart card and other integrated flash applications

From its emergence in the late 1980s as a lower cost alternative to early EEPROM technologies, flash memory has evolved to higher densities and speedsand rapidly growing acceptance in mobile applications.In the process, flash memory devices have placed increased test requirements on manufacturers. Today, as flash device test grows in importance in China, manufacturers face growing pressure for reduced cost-oftest, increased throughput and greater return on investment for test equipment. At the same time, the move to integrated flash packages for contactless smart card applications adds a significant further challenge to manufacturers seeking rapid, low-cost test.     

An improved parallel thinning algorithm with two subiterations

The parallel thinning algorithm with two subiterations is improved in this paper. By analyzing the notions of connected components and passes, a conclusion is drawn that the number of passes and the number of eight-connected components are equal. Then the expression of the number of eight-connected components is obtained which replaces the old one in the algorithm. And a reserving condition is proposed by experiments, which alleviates the excess deletion where a diagonal line and a beeline intersect. The experimental results demonstrate that the thinned curve is almost located in the middle of the original curve connectivelv with single pixel width and the processing speed is high.     

Theoretical analysis of the relationship between the Brillouin gain coefficient and the strain in the optical-fiber sensors

The relation between the power of the Brillouin signal and the strain is one of the bases of the distributed fiber sensors of temperature and strain. The coefficient of the Bfillouin gain can be changed by the temperature and the strain that will affect the power of the Brillouin scattering. The relation between the change of the Brillouin gain coefficient and the strain is thought to be linear by many researchers. However, it is not always linear based on the theoretical analysis and numerical simulation. Therefore, errors will be caused if the relation between the change of the Brillouin gain coefficient and the strain is regarded as to be linear approximately for measuring the temperature and the strain. For this reason, the influence of the parameters on the Brillouin gain coefficient is proposed through theoretical analysis and numerical simulation.     

Novel fiber-optical interferometer with miniaturized probe for in-hole measurements

Today, micro-system technology and the development of new MEMS （Micro-Electro-Mechanical Systems） are emerging rapidly. In order for this development to become a success in the long run, measurement systems have to ensure product quality. Most often, MEMS have to be tested by means of functionality or destructive tests. One reason for this is that there are no suitable systems or sensing probes available which can be used for the measurement of quasi inaccessible features like small holes or cavities. We present a measurement system that could be used for these kinds of measurements. The system combines a fiber optical, miniaturized sensing probe with low-coherence interferometry, so that absolute distance measurements with nanometer accuracy are possible.     

Curved crystal spectrometer for the measurement of X-ray lines from laser-produced plasmas

In order to diagnose the laser-produced plasmas, a focusing curved crystal spectrometer has been developed for measuring the X-ray lines radiated from a laser-produced plasmas. The design is based on the fact that the ray emitted from a source located at one focus of an ellipse will converge on the other focus by the reflection of the elliptical surface. The focal length and the eccentricity of the ellipse are 1350 mm and 0.9586, respectively. The spectrometer can be used to measure the X- ray lines in the wavelength range of 0.2-0.37 nm, and a LiF crystal （200） （2d = 0.4027 nm） is used as dispersive element covering Bragg angle from 30° to 67.5°. The spectrometer was tested on Shengnang- Ⅱ which can deliver laser energy of 60-80 J/pulse and the laser wavelength is 0.35 μm. Photographs of spectra including the 1 s2p ^1P1-1s^2 ^1S0 resonance line（w）, the 1s2p ^3P2-1s^2 1S0 magnetic quadrupole line（x）, the 1s2p ^3P1-1 s^2 ^1S0 intercombination lines（y）, the 1 s2p ^3S~1-1 s^2 ^1S0 forbidden line（z） in helium-like Ti Ⅹ Ⅺ and the 1 s2s2p ^2P3/2-1 s622s ^2S1/2 line（q） in lithium-like Ti Ⅹ Ⅹhave been recorded with a X-ray CCD camera. The experimental result shows that the wavelength resolution（λ/△ 2） is above 1000 and the elliptical crystal spectrometer is suitable for X-ray spectroscopy.     

Preparation and Characterization of TaN ALD Precursors

High purity organic-tantalum precursors for thin film ALD TaN were synthesized and characterized.Vapor pressure and thermal stability of these precursors were studied.From the vapor pressure analysis,it was found that TBTEMT has a higher vapor pressure than any other published liquid TaN precursor,including TBTDET,TAITMATA,and IPTDET.Thermal stability of the alkyl groups on the precursors was investigated using a 1H NMR technique.The results indicated that the tertbutylimino group is the most stable group on TBTDET and TBTEMT as compared to the dialkylamido groups.Thermal stability of TaN precursors decreased in the following order:TBTDET ＞ PDMAT ＞ TBTEMT.In conclusion,precursor vapor pressure and thermal stability were tuned by making slight variations in the ligand sphere around the metal center.     

Electronic Structure of Semiconductor Nanocrystals

This paper reviews our recent development of the use of the large-scale pseudopotential method to calculate the electronic structure of semiconductor nanocrystals, such as quantum dots and wires, which often contain tens of thousands of atoms. The calculated size-dependent exciton energies and absorption spectra of quantum dots and wires are in good agreement with experiments. We show that the electronic structure of a nanocrystal can be tuned not only by its size,but also by its shape. Finally,we show that defect properties in quantum dots can be significantly different from those in bulk semiconductors.     

Teleportation of an arbitrary unknown N-qubit entangled state under the controlling of M controllers

A new quantum protocol to teleport an arbitrary unknown N-qubit entangled state from a sender to a fixed receiver under M controllers(M < N) is proposed. The quantum resources required are M non-maximally entangled Greenberger-Home-Zeilinger (GHZ) state and N-M non-maximally entangled Einstein-Podolsky-Rosen (EPR) pairs. The sender performs N generalized Bell-state measurements on the 2N particles. Controllers take M single-particle measurement along x-axis, and the receiver needs to introduce one auxiliary two-level particle to extract quantum information probabilistically with the fidelity unit if controllers cooperate with it.     

Critical Stage Rule-Based Real Time Dispatch（RTD）System in Highly-Mixed-Products （HMP） FAB

An improving utilization and efficiency of critical equipments in semiconductor wafer fabrication facilities are concerned. Semiconductor manufacturing FAB is one of the most complicated and cost sensitive environments. A good dispatching tool will make big difference in equipment utilization and FAB output as a whole. The equipment in this paper is In-Line DUV Scanner. There are many factors impacting utilization and output on this equipment group. In HMP environment one of the issues is changing of reticule in this area and idle counts due to load unbalance between equipments. Here we'll introduce a rule-based RTD system which aiming at decreasing the number of recipe change and idle counts among a group of scanner equipment in a high-mixed-products FAB.     

Diode-end-pumped Nd:YVO4/LBO lasers with 4.2W continuous-wave output at 457 nm

A continuous-wave (CW) 457 nm blue laser operating at the power of 4.2 W is demonstrated by using a fiber coupled laser diode module pumped Nd: YVO4 and using LBO as the intra-cavity SHG crystal With the optimization of laser cavity and crystal parameters, the laser operates at a very high efficiency. When the pumping power is about 31 W, the output at 457nm reaches 4.2 W, and the optical to optical conversion efficiency is about 13.5% accordingly. The stability of the out putpower is better than 1.2% for 8 h continuously working.