Twisted differential line structure on high-speed printed circuit boards to reduce crosstalk and radiated emission

Differential signaling has become a popular choice for high-speed digital interconnection schemes on printed circuit boards (PCBs), offering superior immunity to crosstalk and external noise. However, conventional differential lines on PCBs still have unsolved problems, such as crosstalk and radiated emission. When more than two differential pairs run in parallel, a line is coupled to the line adjacent to it because all the lines are parallel in a fixed order. Accordingly, the two lines that constitute a differential pair are subject to the differential-mode crosstalk that cannot be canceled out by virtue of the differential signaling. To overcome this, we propose a twisted differential line (TDL) structure on a high-speed multilayer PCB by using a concept similar to a twisted pair in a cable interconnection. It has been successfully demonstrated by measurement and simulation that the TDL is subject to much lower crosstalk and achieves a 13-dB suppression of radiated emission, even when supporting a 3-Gb/s data rate.     

使用双绞差分结构减小印刷电路板上的串扰和辐射发射

随着发展的需要,高速数字电路PCB板上信号速度越来越快,由于差分信号有较强的抗干扰能力,因此用的得越来越普遍。但是,随着上升时间的进一步减小,差分信号的信号完整性问题也变得越来越重要。由于双绞的结构在一定程度上使得干扰相互抵消,从而提高系统对串扰和辐射发射的抵抗能力,因此,近两年来有一种新的双绞差分传输线被引入到布线中。本文从理论上分析了双绞差分线结构减小串扰和辐射发射的机理,并且通过建模仿真验证了其正确性．     

PCB板级双绞互连结构减小感性和容性串扰噪声

非屏蔽双绞线已经被广泛的运用于网络的互联中,双绞的结构能够提高对串扰和辐射发射的抵抗能力。在高速数字电路的PCB板上差分信号变得越来越多。随着上升时间的加快,差分信号的信号完整性问题变得越来越重要。最近,一种新的双绞差分传输线被引入到布线中。文章通过理论和仿真分析了这种双绞差分线结构如何减小串扰和辐射发射。     

防护布线的结构对PCB板级差分对之间串扰的影响

差分传输线具有低辐射和抑制共模噪声的优势,得到了越来越广泛的应用。但是传统的差分线结构不能有效的降低邻近差分对之间的串扰噪声,这将影响到高速系统的信号完整性。文中针对使用防护布线的方法,讨论了三种不同结构的防护砸线,从场的角度对比了它们的电磁屏蔽效果,利用混模S参数分析了它们对于减小串扰噪声的作用。     

High dielectric constant thin film EBG power/ground network for broad-band suppression of SSN and radiated emissions

We experimentally demonstrated the great advantages of a high dielectric constant thin film electromagnetic bandgap (EBG) power distribution network (PDN) for the suppression of power/ground noises and radiated emissions in high-performance multilayer digital printed circuit boards (PCBs). Five-layer test PCBs were fabricated and their scattering parameters measured. The power plane noise and radiated emissions were measured, investigated and related to the PDN impedance. This successfully demonstrated that the bandgap of the EBG was extended more than three times, covering a range of hundreds of MHz using a 1-cm /spl times/ 1-cm EBG cell, the SSN was reduced from 170 mV to 10 mV and the radiated emission was suppressed by 22 dB because of the high dielectric constant thin film EBG power/ground network.     

A rigorous model for radiated emission prediction in PCB circuits

The problem of the radiated emission from printed circuit boards, (PCBs) is theoretically and experimentally investigated. Differential mode and common mode currents are separately studied by means of a rigorous method based on proper Green's functions. The solution of the integral equations for the current distribution, derived from the problem formulation, is numerically achieved by the method of moments. Simulated results are in good agreement with measurements. The final products of this study are masks that establish the maximum allowable currents or voltage values as a function of frequency to comply with CISPR regulation     

Issues in electromagnetic compatibility of integrated circuits: emission and susceptibility

This paper is focused on the electromagnetic compatibility (EMC) of integrated circuits. The introduction gives general keyword definitions and principles for emission and susceptibility. The second part deals with the evolution of integrated circuit design and technology with its consequences on EMC. The third part describes the mechanisms for generating parasitic noise within integrated circuits and the role of the package and on-chip supply network. Next, the standardized measurement methods are described for both parasitic emission characterization (conducted and radiated) and immunity from 1 MHz to 1 GHz. Issues and proposals up to 18 GHz are discussed. The advances in modeling of emission are also addressed, as well as the issues in immunity prediction.     

高速高密度PCB的RE问题

随着数字产品的时钟频率越来越高,信号上升时间（下降时间）越来越短,PCB的RE越来越严重,已逐步成为影响产品EMC性能的重要因素之一,PCB设计过程中必须采取综合措施抑制RE。从高速高密度PCB设计的角度,总结了PCB级RE的主要来源,分析了PCB级RE的基本规律,给出了PCB级RE的抑制对策。讨论与结论对高速高密度P...     

GB/T 22630—2008新增要求和验证

介绍了车载音视频设备电磁兼容标准中增加的有用信号、受试设备工作状态、抗扰度测试的功能状态分类要求及其特殊规定,并对标准中的瞬态电压发射、天线端骚扰电压、辐射骚扰场强、输入抗扰度、天线端射频电压（共模）的抗扰度、典型波形传导抗扰度、辐射抗扰度、静电放电抗扰度进行了测试和验证。     

使用防护布线减小差分传输线间的高频串扰噪声

随着高速电路的不断发展,差分传输线得到了越来越广泛的应用。它具有低辐射和较好的抗共模噪声能力。但是传统的差分线结构不能有效的降低邻近差分对之间的串扰噪声,这将影响到高速系统的信号完整性。文章针对使用防护布线的方法,讨论了三种不同结构的防护布线,在全波电磁仿真软件HFSS中建立了三维物理模型,利用混模S参数分析了它们对于减小串扰噪声的作用,从场的角度对比了它们的电磁屏蔽效果,并对如何使用防护布线提出了一些建议。     

基于机器学习的PCB串扰预测

随着电子系统中逻辑和时钟频率的迅速提高以及信号边沿的不断变抖,串扰成为印刷电路板(PCB)设计人员必须关心的问题。高速电路仿真软件帮助设计人员降低了一定的设计成本,但对串扰的仿真预测仍需花费大量时间。为提高PCB串扰预测的效率,提出一种用于描述PCB的统一数据结构,全面分析了PCB产生串扰的因素,选用自然语言处理(NLP)模型构建了用于PCB串扰预测的系统,成功将PCB串扰预测的时间降至秒级,并拥有73.2%的准确率。     

A 2 Gb/s Bi-Directional Inter-Chip Data Transceiver With Differential Inductors for High Density Inductive Channel Array

A 2 Gb/s bi-directional inter-chip data transceiver is experimentally demonstrated for the first time in 180 nm CMOS technology. Two orthogonal differential inductor pairs are vertically overlapped to make a bi-directional channel. Using these channels, bi-directional communication system is established without any complex circuit techniques. The crosstalk interference problem in channel array is also considered. Differential inductors, due to their noise immunity can make shorter pitches possible in channel array. Compared with the data link with conventional inductor array, this proposed technique achieves 64% area reduction with the same speed.      

The radiation of a rectangular power-bus structure at multiple cavity-mode resonances

The radiation from power-bus structures on high-speed printed circuit boards due to the switching noise current of digital integrated circuits is investigated. The study is based on an analytical cavity-resonator model for a rectangular parallel-plate structure. Based on the application of the field-equivalence principle, the radiated field is calculated from the electric edge-field distribution. For typical board dimensions, several cavity-mode resonances occur within the typical frequency range of interest, leading to relatively high maximum values for radiated emission. The evaluation of the radiation patterns reveals that all (0, nth) resonances have equal maximum amplitudes in the whole mode spectrum. This allows the setting up of an engineering equation for quantifying the noise-current-related maximum radiated field strength, including the dielectric and ohmic loss. Among all geometrical and material parameters, the dielectric thickness is one of the most effective ones to control radiated emission. The theoretical results are well confirmed by accurate measurements carried out in an anechoic room.     

移动终端电源适配器电磁兼容行业标准解读

概述移动终端电源电磁兼容标准YD/T 1312.13制定的需求、意义、覆盖范围及与对应国外标准的区别.解读标准中的适用性范围、辐射骚扰测试、传导连续骚扰测试、瞬态传导骚扰测试、辐射抗扰度测试等新增内容和相应要求.     

The twin-transistor noise-tolerant dynamic circuit technique

This paper describes a new circuit technique for designing noise-tolerant dynamic logic. It is shown that voltage scaling aggravates the crosstalk noise problem and reduces circuit noise immunity, motivating the need for noise-tolerant circuit design. In a 0.35-μm CMOS technology and at a given supply voltage, the proposed technique provides an improvement in noise immunity of 1.8×(for an AND gate) and 2.5×(for an adder carry chain) over domino at the same speed. A multiply-accumulate circuit has been designed and fabricated using a 0.35-μm process to verify this technique. Experimental results indicate that the proposed technique provides a significant improvement in the noise immunity of dynamic circuits (>2.4x) with only a modest increase in power dissipation (15%) and no loss in throughput     

射频电磁场抗扰度测试方法的研究

本文讨论了射频电磁场抗扰度的测试方法。此外,通过模拟单极子天线的空间发射原理证明了在其发射状态下具有很强的空间辐射场强,也为实际检测工作提供了理论依据。     

Controlling radiated emission from a physically largetelecommunication system

This paper deals with the problems that arise when physically large systems, such as a digital switching exchange for high speed broadband applications, must be tested in order to comply with the EN 55022 standard for radiated emission. Simple closed formulas to predict radiated emissions from elementary sources, such as tracks in PCBs, cables, and small apertures, are outlined with their limits of application and verified by measurements. An analysis of the radiation patterns of simple structures and complex systems is also given     

Effects on signal integrity and radiated emission by split reference plane on high-speed multilayer printed circuit boards

Power/ground partitioning has been used to supply multivoltage levels and to isolate power/ground noise in high-speed multilayer printed circuit boards. However, the partitioning of the power/ground plane breaks the current return path of the signal current through either the power plane or the ground plane, which causes undesired effects such as signal distortion, crosstalk, and radiation. To control and suppress these undesired effects, we should understand the electromagnetic mechanism associated with them. In this paper, the mechanism of the reflection and the transmission of the signal by the slotted power/ground plane is well understood through an analysis of measurements based on time-domain reflectometry. Considering the propagation of a slot wave through the slot line on the power/ground plane, we have successfully explained the changes of the transmitted and reflected waveforms. Furthermore, we have numerically and experimentally investigated the effects of the power/ground partitioning on the radiated emission in various structures. Finally, it is confirmed that the employment of a stitching capacitor on the power/ground slot suppresses the signal distortion and the radiated emission significantly. When the size and the location of the stitching capacitor are designed, there should be a compromise between the noise isolation and the guarantee of the return current path, with considering the resonance frequencies of planes by the capacitor.     

Electromagnetic interference (EMI) reduction from printed circuit boards (PCB) using electromagnetic bandgap structures

As digital circuits become faster and more powerful, direct radiation from the power bus of their printed circuit boards (PCB) becomes a major concern for electromagnetic compatibility engineers. In such multilayer PCBs, the power and ground planes act as radiating microstrip patch antennas, where radiation is caused by fringing electric fields at board edges. In this paper, we introduce an effective method for suppressing PCB radiation from their power bus over an ultrawide range of frequencies by using metallo-dielectric electromagnetic band-gap structures. More specifically, this study focuses on the suppression of radiation from parallel-plate bus structures in high-speed PCBs caused by switching noise, such as simultaneous switching noise, also known as Delta-I noise or ground bounce. This noise consists of unwanted voltage fluctuations on the power bus of a PCB due to resonance of the parallel-plate waveguiding system created by the power bus planes. The techniques introduced here are not limited to the suppression of switching noise and can be extended to any wave propagation between the plates of the power bus. Laboratory PCB prototypes were fabricated and tested revealing appreciable suppression of radiated noise over specific frequency bands of interest, thus, testifying to the effectiveness of this concept.     

A Suitable Method for Ecovehicles to Control Surge Voltage Occurring at Motor Terminals Connected to PWM Inverters and to Control Induced EMI Noise

A method that is suitable for ecovehicles, which controls the surge voltage appearing at motor terminals that are connected to a pulsewidth modulation inverter with short leads that are less than the critical cable length (i.e., the shortest length at which full reflection may occur), is described here. Also, a method to control electromagnetic interference (EMI) noise, which is induced by the surge voltage, is discussed. Ecovehicles have the problem where insulation degradation of motors occurs due to the surge voltage being repeatedly applied to motor terminals during long lifecycles. EMI noise such as the shaft current and the radiated noise, which are induced by the generated surge voltage, easily diffuse into other electric devices due to the high-density packaging structure. The diffused EMI noise may cause a malfunction of the vehicle controller. An EMI noise controller is studied, which can meet the high-density packaging requirements for ecovehicles like electric vehicles. The EMI noise controller is attached on the motor terminals and simultaneously suppresses the surge voltage and the noise. After clarifying surge voltage characteristics and a circuit model for expressing the surge phenomenon through experiments and simulations, an EMI noise controller is proposed, which uses a multilayer printed power circuit technique. It is verified through simulations and experiments that the proposed controller has the ability to simultaneously control the surge voltage and the EMI noise, such as the radiated noise and the shaft current (the bearing current), which are induced by the surge voltage.