Electromagnetic characterisation of printed circuit boards

印刷电路板的电磁特性

• 批准号: EP/D048540/1
• 负责人: David Thomas
• 金额: $ 33.56万
• 依托单位: University of Nottingham
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2006
• 资助国家: 英国
• 起止时间: 2006 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=EP%2FD048540%2F1
• 关键词: Electromagnetic; characterisation; printed; circuit; boards

Significant advances have been made in developing circuits driven by fast clocks, thus increasing dramatically processing speeds. Clock rates of a few GHz are now available. Even a few harmonics of the clock rate, takes designs well into the microwave region where printed circuit boards (PCBs) have dimensions of the order of several wavelengths and become efficient radiators of electromagnetic (EM) energy. The increase in clock speed in combination with the driving down of device switching voltage levels is making emissions and susceptibility critical issues in the next generation systems. It is becoming critically important to include electromagnetic compatibility (EMC) very early in the design phase of high speed systems. Design engineers are primarily concerned with circuit based currents and voltages and are normally only marginally aware of the EMC issues. EMC is primarily concerned with the emission of EM fields from devices and the susceptibility of a device to an external EM field. EM field driven issues make circuit geometry as well as network connectivity important for PCBs which are electrically large (compared to wavelength). PCBs are also becoming more complex so that quantifying their EM properties is more difficult. It is of course possible, through detailed 3D EM simulation, to accurately reproduce the EM fields around a PCB but this requires unrealistic computing power and simulation run times. Full field-based tools, although well developed for microwave circuits, cannot deal efficiently with the complexity of modern designs. EMC issues are frequently concerned with harmonic frequencies outside the operating frequency and beyond the range for which device characteristics are accurately quantified. The provision of efficient EMC CAD analysis tools and concepts would be a timely addition to advanced engineering design.The object of this project is to simplify the problem of EM emissions from PCBs as much as possible and to provide design engineers with a simple coherent measure of the performance of a PCB, which can be plugged and played in an EMC analysis package. By this we mean a formulation of simple and general emission equivalents, which can easily be incorporated into full-field EM models for the purpose of assessing EMC interaction of several PCBs in their operating environment. The method proposed is to echo the established IBIS approach for the port characterization of devices which engineers are familiar with. It is proposed to develop and evaluate a technique where the EM emissions and coupling of a PCB are characterized by an array of electric and magnetic dipoles. The way the PCB is segmented and represented by equivalent dipoles will be the subject of extensive investigations as it must offer an acceptable way of replicating emissions. These dipole structures may be active to represent on board sources or passive to represent the coupling between the PCB and the EM environment. Though PCB structures may be complex, resolution of the order of approximately a tenth of a wavelength is normally necessary to accurately represent a device's EM characteristics. An array of equivalent dipoles spaced a few cm apart with their source amplitudes and impedances should, therefore, be sufficient to accurately represent a PCB. Ideally this representation must be invariant under all changes in system conditions in the enclosure or the external environment. In this way the development engineer will have a simple and efficient model, which can be plugged into standard EM field solvers to rapidly prototype a system design for EMC. Also, realistic problems can be tackled at a reasonable computational cost. The proposed EM representation of a PCB will be very powerful as it would be completely general being valid not only for full EM field solvers but also for other semi-analytic intermediate EMC models. Such models allow what if studies to be conducted during the conceptual design phase.

在开发由快速时钟驱动的电路方面已经取得了重大进展，从而显着提高了处理速度。现在可以使用几 GHz 的时钟速率。即使是时钟速率的几个谐波，也可以将设计很好地引入微波区域，其中印刷电路板 (PCB) 的尺寸约为几个波长，并成为电磁 (EM) 能量的有效辐射器。时钟速度的提高与器件开关电压电平的降低相结合，使排放和敏感性成为下一代系统中的关键问题。在高速系统的设计阶段尽早纳入电磁兼容性 (EMC) 变得至关重要。设计工程师主要关注基于电路的电流和电压，通常对 EMC 问题知之甚少。 EMC 主要关注设备的电磁场发射以及设备对外部电磁场的敏感性。电磁场驱动的问题使得电路几何形状以及网络连接对于电气尺寸较大（与波长相比）的 PCB 非常重要。 PCB 也变得越来越复杂，因此量化其电磁特性变得更加困难。当然，通过详细的 3D 电磁仿真，可以准确地再现 PCB 周围的电磁场，但这需要不切实际的计算能力和仿真运行时间。完整的基于现场的工具虽然针对微波电路开发得很好，但无法有效地处理现代设计的复杂性。 EMC 问题通常与工作频率之外以及设备特性精确量化范围之外的谐波频率有关。提供高效的 EMC CAD 分析工具和概念将是对先进工程设计的及时补充。该项目的目标是尽可能简化 PCB 的电磁发射问题，并为设计工程师提供一种简单的连贯测量方法。 PCB的性能，可在EMC分析包中即插即用。我们指的是简单且通用的发射当量的公式，可以轻松地将其合并到全场电磁模型中，以评估多个 PCB 在其操作环境中的 EMC 相互作用。所提出的方法是呼应工程师所熟悉的用于设备端口特性分析的已建立的 IBIS 方法。建议开发和评估一种通过电偶极子阵列和磁偶极子阵列来表征 PCB 的电磁发射和耦合的技术。 PCB 的分段和由等效偶极子表示的方式将成为广泛研究的主题，因为它必须提供一种可接受的复制发射的方式。这些偶极子结构可以是有源的以表示板载源，也可以是无源的以表示 PCB 和 EM 环境之间的耦合。尽管 PCB 结构可能很复杂，但通常需要大约十分之一波长量级的分辨率才能准确表示设备的电磁特性。因此，间隔几厘米的等效偶极子阵列及其源幅度和阻抗应该足以准确地表示 PCB。理想情况下，这种表示必须在外壳或外部环境中系统条件的所有变化下保持不变。通过这种方式，开发工程师将拥有一个简单而高效的模型，可以将其插入标准电磁场求解器中，以快速构建 EMC 系统设计原型。此外，可以以合理的计算成本解决现实问题。所提出的 PCB 电磁表示将非常强大，因为它完全通用，不仅适用于完整的电磁场求解器，而且适用于其他半解析中间 EMC 模型。这些模型允许在概念设计阶段进行假设研究。

项目成果

PCB electromagnetic emissions prediction from equivalent magnetic dipoles found from near field scans

根据近场扫描发现的等效磁偶极子进行 PCB 电磁辐射预测

• 发表时间: 2008
• 作者: D Thomas

Measurement and Simulation of Near Field Emissions from Microstrip Lines

微带线近场发射的测量和仿真

• 作者: David Thomas (Co

Modeling Electromagnetic Emissions From Printed Circuit Boards in Closed Environments Using Equivalent Dipoles

使用等效偶极子对封闭环境中印刷电路板的电磁发射进行建模

• DOI: 10.1109/temc.2010.2044181
• 发表时间: 2010-03-22
• 期刊: IEEE Transactions on Electromagnetic Compatibility
• 影响因子: 2.1
• 作者: Xin Tong;David W. P. Thomas;A. Nothofer;P. Sewell;C. Christopoulos
• 通讯作者: C. Christopoulos

Optimised Equivalent Dipole Model of PCB Emissions Based on Genetic Algorithms

基于遗传算法优化的PCB发射等效偶极子模型

• 作者: Xin Tong (Co

PCB Electromagnetic Emissions Prediction from Equivalent Magnetic Dipoles found from Near Field Scans

根据近场扫描发现的等效磁偶极子预测 PCB 电磁辐射

• 作者: Xin Tong (Co