印刷电路板供电系磁性材料涂层的应用

印刷电路板（PCB）的电磁兼容问题,随着数字电路的工作频率越来越高而变得尤为重要。本文以印刷电路板中的电源接地层供电系构造为切入点,讨论与其相关的电磁兼容问题。在高频段,印刷电路板的电源和接地层构造相当于一个平行平板谐振器,对周围的电路产生电磁干扰（EMI）。基于全腔模模型,已经发展了用于高效准确计算供电系阻抗的快速算法。利用此算法,通过计算机仿真,结果表明PCB电源接地层导体内侧增加磁性材料涂层能够提高表面阻抗,进而减小端口输入阻抗的谐振峰并改善信号完整性。     

Numerical and experimental investigation of radiation caused by the switching noise on the partitioned DC reference planes of high speed digital PCB

Influence of the partitioning and bridging of the power/ground planes on the radiation caused by the switching noise on the dc reference planes is investigated both theoretically and experimentally. Based on the three-dimensional finite-difference time-domain modeling, the electromagnetic interference (EMI) performance of the partitioned power/ground planes is studied. Radiated emission at the 3-m distance from the tested boards is measured in a fully anechoic chamber. The measured and the numerical results agree generally well. The radiation behavior of four kinds of partitioned configuration of the power/ground planes is studied. It is found that completely isolating the noise source by the etched slits, or moats, significantly reduces the radiation level at the frequencies near resonance. However, bridges connecting two sides of the moat not only significantly degrade the ability of the EMI protection of the moat, but also excite a new low-frequency resonant mode. The effect of the geometrical parameters, such as the moat size, moat location, bridge width, and bridge position, on the radiation behavior of the printed circuit board is considered. The radiation mechanism of the EMI behavior of the partitioned dc reference planes is discussed.     

一种基于互补环缝谐振器抑制SSN的新方法

针对高速PCB上抑制同步开关噪声(SSN)的问题,提出了一种将互补环缝谐振器(CSRR)刻蚀在电源平面上,抑制电源/地平面间的电场波动噪声传播的方法。采用基于有限元算法的HFSS软件对该结构进行仿真分析,结果表明:与理想参考平面和电磁带隙结构相比,刻蚀了该CSRR结构的电源分配网络具有较好的宽带全向SSN噪声抑制能力,在抑制深度为-40 dB时,其阻带覆盖从0.26 GHz到超过20 GHz以上的频率范围。     

An electromagnetic crystal power substrate with efficient suppression of power/ground plane noise on high-speed circuits

An electromagnetic crystal power substrate (ECPS) in a high-speed circuit package is proposed for suppressing the power/ground planes noise (P/GPN) and the corresponding electromagnetic interference (EMI). The ECPS is simply realized by periodically embedding the high dielectric-constant rods into the conventional package substrate between the continuous power and ground planes. With a small number of embedded rods and low rod filling ratio, the proposed ECPS design can efficiently eliminate the noise of 30dB in average within several designed stopbands. In addition, the radiation or EMI resulting from the P/GPN is also significantly reduced over 25dB in the stopbands. The excellent noise and EMI suppression performance for the proposed structure are verified both experimentally and numerically. Reasonably good consistency is seen.     

PCB design techniques for lowest-cost EMC compliance .1

Application of good EMC (electromagnetic compatibility) practices to the design of printed circuit boards (PCBs) usually helps to achieve the EMC performance required of equipment and systems at much lower cost than alternative EMC measures at higher levels of integration, such as whole-product shielding. EMC design is a complex topic, but the proven best EMC practices for generalised PCB layout can be fairly simply stated and grouped into five techniques, which interact with each other to give dramatic improvements in EMC performance. This paper discusses the techniques of circuit segregation, interface suppression and the use of ground and power planes     

介质型EBG结构对同步开关噪声抑制的有限元分析

研究了介质型电磁带隙结构对高速电路中电源/ 地平面间同步开关噪声的抑制作用。该介质型电磁带隙结构在抑制同步开关噪声的同时未破坏高速信号的电流返回路径,使高速信号的信号完整性得以保持。利用电磁场有限元方法将电源/地平面间同步开关噪声抑制的三维问题转化成二维问题进行处理,提高了计算效率。分析了介质型电磁带隙结构的介电常数对噪声抑制带宽的影响,利用了三维全波电磁场仿真软件HFSS对二维数值结 果进行仿真验证,仿真结果与数值计算结果基本吻合,验证了二维数值算法的正确性。     

Novel Planar Electromagnetic Bandgap Structures for Mitigation of Switching Noise and EMI Reduction in High-Speed Circuits

Planar electromagnetic bandgap (EBG) structures with novel meandered lines and super cell configuration are proposed for mitigating simultaneous switching noise propagation in high-speed printed circuit boards. An ultrawide bandgap extending from 250 MHz to 12 GHz and beyond is demonstrated by both simulation and measurement, and a good agreement is observed. These perforated EBG-based power planes may cause spurious and unwanted radiation. In this paper, leakage radiation through these imperfect planes is carefully investigated. It is found that the leakage field from these planar EBG structures is highly concentrated around the feed point, and the field intensity is attenuated dramatically when passing across several periods of patches. A novel concept of using these EBG structures for electromagnetic interference reduction is also introduced. Finally, the impact of power plane with EBG-patterned structures on signal integrity is studied.     

Analysis of power delivery network constructed by irregular-shaped power/ground plane including densely populated via-hole

The high speed and low power trend has imposed more and more importance on the design of the power distribution network (PDN) using multilayer printed circuit boards (PCBs) for modern microelectronic packages. This paper presents a fast and efficient analysis methodology in frequency domain for the design of a PDN with a power/ground plane pair, which considers the effect of irregular shape of the power/ground plane and densely populated via-holes. The presented method uses parallel-plate transmission line theory with equivalent circuit model of unit-cell grid considering three-dimensional geometric boundary conditions. Characteristics of PDNs implemented by perforated planes including a densely populated via-hole structure is quantitatively determined based on full-wave analysis using the finite-difference time-domain (FDTD) periodic structure modeling method and full-wave electromagnetic field solver. Using a circuit simulator such as popularly used SPICE and equivalent circuit models for via-hole structure and perforations, the authors have analyzed input-impedance of the power/ground plane pair. Since the presented method gives an accurate and fast solution, it is very useful for an early design of multilayer PCBs.     

Miniaturised electromagnetic bandgap structures for broadband switching noise suppression in PCBs

A novel concept for ultra-wideband suppression of switching noise in high-speed printed circuit boards (PCBs) is proposed, implemented and tested. This concept consists of using non-symmetrical, embedded electromagnetic bandgap (EEBG) structures in conjunction with material with high dielectric constants. The proposed design modifies the classical EEBG structures to achieve a high degree of miniaturisation and an unprecedented broadband suppression of switching noise.     

高速PCB的地线布线设计

本文针对高速PCB板信号接地设计中存在接地噪声及电磁辐射等问题,提出了高速PCB接地模型,并从PCB设计中布线策略的分析和去耦电容的使用等几个方面讨论了解决高速PCB板的接地噪声和电磁辐射问题的方法.     

A novel power planes with low radiation and broadband suppression of ground bounce noise using photonic bandgap structures

A novel power/ground planes design for eliminating the ground bounce noise (GBN) in high-speed digital circuits is proposed by using low-period photonic bandgap (PBG) structure. Keeping solid for the ground plane and designing low-period PBG pattern on the power plane, the proposed structure omni-directionally behaves highly efficient suppression of GBN (over 50 dB) within broadband frequency range from 1 GHz to 4 GHz. Although the power plane has low-period perforation, the proposed structure still performs with relatively low radiation within the stopband compared with the solid power/ground planes. The low radiation and high suppression of the GBN for the proposed structure are checked both experimentally and numerically. Good consistency is seen.     

Double-Stacked EBG Structure for Wideband Suppression of Simultaneous Switching Noise in LTCC-Based SiP Applications

We propose a novel electromagnetic bandgap (EBG) structure with a significantly extended noise isolation bandwidth, called a double-stacked EBG (DS-EBG) structure, fabricated on a low-temperature co-fired ceramic (LTCC) multilayer substrate. The DS-EBG structure was devised for wideband suppression of simultaneous switching noise (SSN) coupling in system-in-package (SiP) applications. Our design approach was enabled by combining two EBG layers embedded between the power and ground planes. The two EBG layers had different bandgaps from using different cell sizes. Enhanced wideband suppression of the SSN coupling was validated using a 11.4-GHz noise stop bandwidth with 30-dB isolation in time and frequency domain measurements up to 20GHz.     

Partial EBG Structure with DeCap for Ultra‐wideband Suppression of Simultaneous Switching Noise in a High‐Speed System

To supply a power distribution network with stable power in a high‐speed mixed mode system, simultaneous switching noise caused at the multilayer PCB and package structures needs to be sufficiently suppressed. The uniplanar compact electromagnetic bandgap (UC‐EBG) structure is well known as a promising solution to suppress the power noise and isolate noise‐sensitive analog/RF circuits from a noisy digital circuit. However, a typical UC‐EBG structure has several severe problems, such as a limitation in the stop band's lower cutoff frequency and signal quality degradation. To make up for the defects of a conventional EBG structure, a partially located EBG structure with decoupling capacitors is proposed in this paper as a means of both suppressing the power noise propagation and minimizing the effects of the perforated reference plane on the signal quality. The proposed structure is validated and investigated through simulation and measurement in both frequency and time domains.     

The effect of test system impedance on measurements of groundbounce in printed circuit boards

Based on the 3D-FDTD approach, an efficient equivalent model employing the embedded resistive voltage source is proposed to simulate the effect of test system impedance on the measurement of the ground bounce noise for the power planes structure in the printed circuit boards (PCB). Compared with the measured results by vector network analyzer, this equivalent model well predicts the impedance behavior of the V_cc/GND power planes. The influences of different probe loading conditions of the test system on the measurement of impedance behavior are studied. It is found that the effects of the probing loads on the measurement of the ground bounce noise is significant at the frequencies near the dc point and resonance, but the influences of the probes are small at the frequencies far from resonance. In addition, the transfer characteristics of the power bus in the realistic digital circuits with decoupling capacitance being considered are simulated in the FDTD model. The difference of the transfer behavior between the realistic case without coaxial feed and the measured results with probing effects is also numerically compared. We find that the ground bounce noise in the real circuit can be accurately measured at most frequencies, where the power planes act in very low impedance, except at the frequencies near dc and resonance frequencies, where the power planes behave in relatively higher impedance characteristics     

Simultaneous switching noise mitigation in PCB using cascaded high-impedance surfaces

A novel concept for ultra-wide-bandwidth suppression of simultaneous switching noise (SSN) in high-speed printed circuit boards (PCBs) is proposed and implemented. This method consists of cascading high-impedance surfaces (HIS) with different stop bands, creating rejection over a wide frequency region. A PCB with the cascaded HIS design has been successfully fabricated and tested.     

结合电磁带隙结构和磁性材料的PCB电源接地层设计

在印制电路板的设计中,供电系阻抗谐振所引起的噪声和电磁干扰问题一直是设计人员关注的焦点。已有的研究显示,适当的电磁带隙（EBG）结构可以有效地降低供电系的电磁干扰。本文通过运用基于快速算法和分解元法的计算机仿真,研究供电系EBG结构中采用磁性材料后的阻抗特性。研究表明,在供电系内侧增加磁性材料涂层,能在原有基础上进一步抑制电磁干扰。     

基于有限元法的高频开关电源PCB电磁兼容设计与仿真

在高频开关电源的设计中,功率开关器件在高频下的通断会产生强大的EMI,所以不可避免的会出现电磁兼容问题。这篇文章应用有限元法分别对自动布线后的高频开关电源PCB与按照电磁兼容设计规则布线后的PCB进行仿真,得到其在200 MHz、600 MHz、1 GHz频率处的近场辐射参数。仿真结果表明:自动布线生成的高频开关电源PCB近场辐射的范围和数值均较大,电磁干扰较强。根据电磁兼容的相关规则对PCB进行优化后,近场辐射的范围和数值均有所减小,提高了PCB板的电磁兼容性。     

Modeling and measurement of simultaneous switching noise coupling through signal via transition

The signal via is a heavily utilized interconnection structure in high-density System-on-Package (SoP) substrates and printed circuit boards (PCBs). Vias facilitate complicated routings in these multilayer structures. Significant simultaneous switching noise (SSN) coupling occurs through the signal via transition when the signal via suffers return current interruption caused by reference plane exchange. The coupled SSN decreases noise and timing margins of digital and analog circuits, resulting in reduction of achievable jitter performance, bit error ratio (BER), and system reliability. We introduce a modeling method to estimate SSN coupling based on a balanced transmission line matrix (TLM) method. The proposed modeling method is successfully verified by a series of time-domain and frequency-domain measurements of several via transition structures. First, it is clearly verified that SSN coupling causes considerable clock waveform distortion, increases jitter and noise, and reduces margins in pseudorandom bit sequence (PRBS) eye patterns. We also note that the major frequency spectrum component of the coupled noise is one of the plane pair resonance frequencies in the PCB power/ground pair. Furthermore, we demonstrate that the amount of SSN noise coupling is strongly dependent not only on the position of the signal via, but also on the layer configuration of the multilayer PCB. Finally, we have successfully proposed and confirmed a design methodology to minimize the SSN coupling based on an optimal via positioning approach.     

高速电路中地弹噪声抑制的研究

研究了高速电路领域中的一类重要的电源完整性问题,即电源地平面之间激发的地弹噪声问题。地 弹噪声的存在严重破坏了电源/ 地平面的完整性,导致供电电压幅度的不稳定,严重之时甚至导致电路的误判。针 对这一问题,设计了一种超宽带电磁带隙结构。实验结果表明,这种电磁带隙结构可以在0. 5 ~5. 5GHz(11 倍频程) 频段内实现优于30dB 的噪声抑制能力。文章还探讨了带隙结构作为电源平面时信号传输的完整性。研究表明,如 果电路工作频率高达GHz 或更高,在电源/ 地平面采用这种带隙结构,可以有效地避免地弹噪声带来的影响,并保证 电源和信号的完整性。     

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.