高速PCB串扰分析及其最小化

技术进步带来设计的挑战,在高速、高密度PCB设计中,串扰问题日益突出.本文就串扰原理和对信号完整性影响进行分析,并在此基础上提出了高速P C B设计中串扰最小化的方法.     

Crosstalk bandwidth and stability analysis in graphene nanoribbon interconnects

Based on transmission line modeling (TLM), and using the Nichols chart, we present a bandwidth and stability analysis, together with step time responses, for coupled multilayer graphene nanoribbon (MLGNR) interconnects that is inquired for the first time. In this analysis, the dependence of the degree of crosstalk relative stability for coupled MLGNR interconnects comprising of both capacitive and mutual-inductive couplings between adjacent MLGNR has been acquired. The obtained results show that with increasing the length or decreasing the width of the MLGNRs, the stability in near-end output increases. While, any increase in the length or width of MLGNRs, decrease the stability of far-end output. Also, by increasing capacitive coupling or decreasing inductive coupling, the near-end output becomes more stable, and the far-end output becomes less stable. Moreover, any increase in the length or capacitive coupling, decreases the bandwidth, whereas any increase in the width or inductive coupling, increases the bandwidth. Finally, transient simulations with Advanced Design System (ADS) show that the model has an excellent accuracy.     

Adaptive Techniques for Joint Optimization of XTC and DFE Loop Gain in High‐Speed I/O

High‐speed I/O channels require adaptive techniques to optimize the settings for filter tap weights at decision feedback equalization (DFE) read channels to compensate for channel inter‐symbol interference (ISI) and crosstalk from multiple adjacent channels. Both ISI and crosstalk tend to vary with channel length, process, and temperature variations. Individually optimizing parameters such as those just mentioned leads to suboptimal solutions. We propose a joint optimization technique for crosstalk cancellation (XTC) at DFE to compensate for both ISI and XTC in high‐speed I/O channels. The technique is used to compensate for between 15.7 dB and 19.7 dB of channel loss combined with a variety of crosstalk strengths from 60 mV_p‐p to 180 mV_p‐p adaptively, where the transmit non‐return‐to‐zero signal amplitude is a constant 500 mV_p‐p.     

Temperature dependant crosstalk analysis in coupled single‐walled carbon nanotube (SWCNT) bundle interconnects

The temperature‐dependent, crosstalk‐induced, noise voltage waveform and its frequency spectrum, in capacitive coupled single‐walled carbon nanotube (SWCNT) bundle interconnects, at the far end of victim line, have been analyzed at 22‐nm technology node. A similar analysis is performed for copper interconnects and a comparison is made between the results of these two analyses. The SPICE simulation results reveal that at temperature variations ranging from 300 to 500 K, compared with conventional metal (copper) conductors, crosstalk noise voltage levels in CNT, at the far end of victim line, are significantly low. Simulated results further reveal that, with rise in interconnect temperatures, compared with copper interconnects, coupled interconnects of SWCNT bundle filter more noise frequency components. Based on these comparative results, an improved model for extracting inter‐bundle, real life, coupling capacitances between SWCNT bundles has been proposed. Copyright © 2014 John Wiley & Sons, Ltd.     

Important parameters that influence crosstalk in multiconductor transmission lines

Transient surges in one of the overhead conductors, due to direct lightning strikes, causes crosstalk [C.R. Paul, Analysis of Multiconductor Transmission Lines, John Wiley & Sons, Inc., 1994; C.R. Paul, Introduction to Electromagnetic Compatibility, John Wiley & Sons, Inc., 1992] in other adjacent conductors. It is a common electromagnetic interference (EMI) phenomenon observed in power lines, communication lines and electrified railway lines. In this paper we investigate the crosstalk in multiconductor transmission lines (MTLs) above finitely conducting ground as a function of ground conductivity, heights of the receptor conductor and the terminal loads. For receptor conductor close to the ground, compared to the emitter conductor [C.R. Paul, Analysis of Multiconductor Transmission Lines, John Wiley & Sons, Inc., 1994; C.R. Paul, Introduction to Electromagnetic Compatibility, John Wiley & Sons, Inc., 1992], the decrease in ground conductivity increases the crosstalk peak currents at near end (end near to the source in the emitter conductor) of the receptor conductor, but at the far end it could either increase or decrease depending upon the line height and ground conductivity.     

Optical and electrical multilevel storage in organic memory passive matrix arrays

The integration of organic memory diodes, based on photochromic transduction layers, into a simple cross-bar passive matrix array is presented. We show that the high rectification ratios of these diodes successfully suppresses crosstalk effects in these devices, thus avoiding the necessity to integrate additional diodes or transistors. We compare the passive matrix devices’ performance to that of non-crossbar reference devices and discuss their performance limitations related to edge effects, which are a consequence of the fabrication process. Finally, we show that the analogue response of the current density to incremental switching of the transduction layer can be used for multi-level programming of the memory elements with no inherent limit to the number of intermediate states. We demonstrate the successful read-out of 8 current levels in a prototype device via both optical and electrical writing procedures.     

Analysis on Additional Crosstalk Caused by Oblique Incident Ray on PIN Detector Array

The crosstalk caused by oblique incident ray on a PIN detector array is analyzed.An integral expression of crosstalk factor in relation to incident angle and structure parameters is deduced and the correctness of the deduction is tested and verified.     

基于光谱辐射度法的PDP显示屏色串扰评价

色串扰是 PDP 显示屏的一种特殊缺陷.本文先介绍了色串扰的起因,然后提出了一种新的基于光谱辐射度法的色串扰评价方法.该方法首先测量红、绿、蓝单色发光单元的光谱功率分布,然后在显示屏红场、绿场、蓝场下分别测量包含有足够象素(如 500 象素)显示区域的光谱功率分布,由此建立有关于串扰评价系数的关系式.选择单色发光单元测试结果中包含有足够强光谱功率的波段数据参与计算,计算得到上述串扰评价系数.本文分析了基于该方法的试验结果,并指出光谱辐射度法对于 PDP 显示屏而言是一种有效的色串扰评价方法.     

扁平线缆电磁-热耦合场的协同仿真分析研究

电子设备中线缆所处工作环境越来越复杂,线缆之间的电磁串扰以及电磁损耗带来的热效应日益严重。针对这一问题,在电磁场、温度场和多场耦合相关理论的基础上,具体分析了线缆的电磁场和温度场相互影响的显著程度,基于在温度变化较小的情况下线缆的材料属性变化不明显,为了简化研究手段,只关注了从电磁场到温度场的单方向耦合。建立了线缆电磁-热耦合三维有限元仿真分析模型,采用Ansoft HFSS进行电磁场分析,同时将其分析所得电磁损耗作为发热源加载到Ansofte Physics中进行温度场分析。采用这种协同仿真方案,最终得到了不同线缆间距、绝缘层厚度和传输信号频率对电磁串扰及热效应带来的影响。     

Energy reduction through crosstalk avoidance coding in networks on chip

Commercial designs are currently integrating from 10 to 100 embedded processors in a single system on chip (SoC) and the number is likely to increase significantly in the near future. With this ever increasing degree of integration, design of communication architectures for large, multi-core SoCs is a challenge. Traditional bus-based systems will no longer be able to meet the clock cycle requirements of these big SoCs. Instead, the communication requirements of these large multi processor SoCs (MP-SoCs) are convened by the emerging network-on-chip (NoC) paradigm. Crosstalk between adjacent wires is an important signal integrity issue in NoC communication fabrics and it can cause timing violations and extra energy dissipation. Crosstalk avoidance codes (CACs) can be used to improve the signal integrity by reducing the effective coupling capacitance, lowering the energy dissipation of wire segments. As NoCs are built on packet-switching, it is advantageous to modify data packets by including coded bits to protect against the negative effects of crosstalk. By incorporating crosstalk avoidance coding in NoC data streams and organizing the CAC-encoded data packets in an efficient manner, so that total number of encoding/decoding operations can be reduced over the communication channel, we are able to achieve lower communication energy, which in turn will help to decrease the overall energy dissipation.