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.     

Bandwidth Enhancement for SSN Suppression Using a Spiral‐Shaped Power Island and a Modified EBG Structure for a λ/4 Open Stub

This paper proposes a spiral‐shaped power island structure that can effectively suppress simultaneous switching noise (SSN) when the power plane drives high‐speed integrated circuits in a small area. In addition, a new technique is presented which greatly improves the resonance peaks in a stopband by utilizing λ/4 open stubs on a conventional periodic electromagnetic bandgap (EBG) power plane. Both proposed structures are simulated numerically and experimentally verified using commercially available 3D electromagnetic field simulation software. The results demonstrate that they achieve better SSN suppression performance than conventional periodic EBG structures.     

基于三种尺寸L-Bridge单元的超宽带电磁带隙结构

通过把3 种不同尺寸的L-bridge 单元进行组合,在多层PCB 板的电源层上,设计了一种新的多周期平面型超宽带电磁带隙(Electromagnetic Band Gap, EBG)结构,可用于抑制数字电路系统中的同步开关噪声(Simultaneous Switching Noise, SSN)。利用HFSS 软件对该EBG 结构进行了建模和仿真,并在仿真基础上制作了电路实物,实测与仿真结果吻合良好。组合结构EBG 比传统L-bridge EBG 的阻带宽度有明显提高,当抑制深度为-40 dB 时,具有从0.8 GHz 到9.5 GHz 的超宽带阻带特性。     

一种新型多周期平面电磁带隙结构

根据不同周期平面电磁带隙(EBG)结构所具有的不同带隙特性以及平面EBG结构的等效电路,提出一种新型多周期平面EBG结构。通过Ansoft HFSS软件对该EBG结构的电磁带隙特性进行仿真验证。结果表明:所提出的EBG结构抑制深度为-30dB时,阻带范围为0.7~8.4GHz,阻带宽度为7.7GHz.相对于传统大周期和小周期平面EBG结构,其阻带宽度分别增加2.1GHz和1.2GHz.仿真结果也表明新型EBG结构可以有效抑制同步开关噪声(SSN),并为展宽平面EBG结构的禁带带宽提供一种新方法。最后,通过时域仿真验证新结构具有较好的信号完整性。     

一种抑制同步开关噪声的超宽带电磁带隙结构

针对谐振电磁带隙（Electromagnetic Band Gap, EBG）结构带宽比较窄的问题,通过研究EBG的等效电路模型,提出了一种新颖的垂直级联型EBG结构.同时使用Ansoft HFSS软件对所设计的结构进行仿真分析及验证.仿真结果表明：新结构在抑制深度为-40 dB时,阻带范围为0.75～15.7 GHz,具有14.95 GHz噪声抑制的超带宽特性.与同尺寸的传统单过孔Mushroom EBG结构相比,带宽增加3.65 GHz,相对带宽提高32.3 %.新结构为改善EBG结构抑制噪声带宽提供一种理论参考的新方法.     

1D介质型EBG噪声隔离性能的有限元建模分析

提出了一种分析多层印刷电路板电源分配网络（power distribution network, PDN）中一维（1D）介质型电磁带隙（electromagnetic band-gap, EBG）结构噪声隔离性能的1D有限元数值计算方法. 将1D介质型EBG的3D结构简化为1D有限元模型,通过直接求解波动方程获得传输系数T、反射系数R以及散射参数S. 利用R-T曲线可直观地判定频率禁带,而采用分贝表示的S₂₁参数则更方便评价噪声隔离度. 根据介质型EBG的周期数、介电常数和周期长度等参数对噪声隔离性能影响的仿真结果,针对少周期、不完全禁带EBG结构提出了先采用多周期EBG结构预测禁带,再通过调整介电常数和周期长度扩展禁带和增强噪声隔离度的两阶段设计方法. 采用3D全波电磁仿真验证了1D有限元算法的合理性.     

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。     

抑制同步开关噪声的超带宽电磁带隙结构研究

针对抑制印刷电路板中电源平面与接地平面之间的同步开关噪声问题,提出了一种新型的二维电磁带隙结构（BSEBG）。这一新型结构的设计基于在正方形金属贴片的四角刻蚀出折线型缝隙以降低贴片的有效电容,应用折线以增加相邻贴片的有效电感,单元晶格由折线与含有缝隙的正方形金属贴片桥接构成。仿真分析结果表明：相比于同参数的ZbridgedEBG电磁带隙结构,当抑制深度定义为-30dB时,BSEBG结构阻带范围从220MHz到超过20GHz,相对带宽增加了约15％,阻带下限截止频率降低了110MHz。     

Multi‐stack Technique for a Compact and Wideband EBG Structure in High‐Speed Multilayer Printed Circuit Boards

We propose a novel multi‐stack (MS) technique for a compact and wideband electromagnetic bandgap (EBG) structure in high‐speed multilayer printed circuit boards. The proposed MS technique efficiently converts planar EBG arrays into a vertical structure, thus substantially miniaturizing the EBG area and reducing the distance between the noise source and the victim. A dispersion method is presented to examine the effects of the MS technique on the stopband characteristics. Enhanced features of the proposed MS‐EBG structure were experimentally verified using test vehicles. It was experimentally demonstrated that the proposed MS‐EBG structure efficiently suppresses the power/ground noise over a wideband frequency range with a shorter port‐to‐port spacing than the unit‐cell length, thus overcoming a limitation of previous EBG structures.     

CO-OFDM系统中基于维纳滤波的相位噪声ICI抑制算法

针对相干光正交频分复用(CO-OFDM)通信系统中相位噪声引起的载波间干扰(ICI)问题,提出一种基于维纳滤波的相位噪声ICI抑制算法。算法不需要改变OFDM符号原有的结构,只需要利用相位噪声预先得到的统计数据,通过相关计算,得到ICI的修正项。由于没有在OFDM符号中添加额外的辅助数据,所以与ICI自消除算法相比,所提出的ICI抑制算法具有较高的频谱利用率。仿真结果表明,在相位噪声比率为10-4级别时,基于迭代检测的ICI消除算法的误码率(BER)趋于10-4,出现错误平层;而本文所提出的ICI抑制算法能够有效地降低错误平层,改善BER性能。     

Phase noise approximation analysis for the OFDM system

The influence of phase noise (PN) present at the access point (AP) and mobile terminator (MT) may degrade the performance in orthogonal frequency division multiplexing (OFDM) system, because the OFDM system is sensitive to the PN.The method of PN approximation based on the PN power spectrum was proposed to combat the influence of the PN present.The idea of the PN cancellation is the PN is approximated for the sum of the different frequency between the AP and the MT as well as Doppler shift supposing that the fixed different frequency during several OFDM symbols are identical, so the variable phase may be considered as the combination of the fixed partition and the random partition.The approximation method is utilized to remove the fixed and the random phase partition so that the signal-to-noise ratio (SNR) may be improved.The analysis and the simulation proposed show that the method may effectively improve the performance of the OFDM system.     

Research on periodic switching frequency modulation for conducted EMI suppressing in power converter

This paper is devoted to explore modulation techniques with deterministic profiles reducing the peak EMI in a power converter. In this paper, the effect of primary modulation parameters such as modulation profile, modulation index and modulation frequency on peak EMI suppression is numerically simulated and discussed while a fully integrated spread spectrum clock generator (SSCG) with triangular modulation is presented whose major advantages are good robustness, small size and low-power consumption. The proposed SSCG has been applied to a fly-back switching converter and the results of the experiment confirm the proposed circuit.     

Merging a DSP-Oriented Signal Integrity Technique and SW-Based Fault Handling Mechanisms to Ensure Reliable DSP Systems

Hereafter, we present an approach aiming to improve the reliability of digital signal processing (DSP) systems operating in real noisy (electromagnetic interference—EMI) environments. The approach is based on the coupling of two techniques: the DSP-oriented signal integrity improvement technique deals with increasing the signal-to-noise ratio (SNR) and is essentially a modification of the classic Recovery Blocks Scheme. The second technique, named SW-based fault handling aims to detect in real-time data- and control-flow faults throughout modifications of the processor code. When compared to conventional approaches using Fast Fourier Transform (FFT) and Hamming Code, the primary benefit of such an approach is to improve system reliability by means of a considerably low complexity, reasonably low performance degradation and, when implemented in hardware, with reduced area overhead. Aiming to illustrate the proposed approach, we implemented a HW/SW prototype to operate as a speech recognition system (SRS). This prototype was tested under a home-tailored EMI environment according to the IEC 61000-4-29 International Standard Normative. The obtained results indicate that the proposed approach can effectively improve the reliability of DSP systems operating in real noise (EMI) environments.     

光纤传感器光源及驱动电路关键技术的研究

随着光纤传感技术的迅速发展,光源及其稳定性对光纤传感器的性能具有重要影响。本文介绍了各种光源的工作原理和性能特点,研究了驱动电路的关键技术及发展现状,分析了其中的主要的电磁干扰现象并给出了相应的解决方法。     

CO-OFDM系统中一种基于卡尔曼滤波的三阶相位噪声补偿算法

在相干光正交频分复用系统(CO-OFDM)中,相位噪 声的方差随着激光器线宽的增加而增加,从而在频域引入 更大载波间干扰,对系统的性能造成极大的影响,同时调制方案阶数的增加会使系统对相位 噪声更加敏感。针对激 光器线宽较大和采用高阶调制的系统,提出了一种基于卡尔曼滤波的三阶相位噪声补偿算法 。算法的3个阶段为 时域相位噪声粗补偿、频域残余CPE消除和时域相位噪声精补偿,并给出了算法3个阶段的数 学模型。所提出算法 与现有的其它几种算法进行了仿真对比分析表明,在激光器线宽较大时,所提出算法具有更 低的误码率(BER),能较大幅度的提高CO-OFDM系统对激光 器线宽的容忍度。     

基于相位噪声分析补偿的CO-OFDM系统信道估计研究

针对相干光正交频分复用(CO-OFDM)系统中 光纤的色散、信道噪声以及激光器 相位噪声对系统可靠性的降低,提出了相位噪声分析补偿(APNC,analysis of phase noise compensation)的信道估计算法。APNC算法以最小二乘(LS)算法为基础,先通过信道冲激响 应加窗(IRW)算法,将信道冲激响应长度以外的噪声滤除,保证了信道冲激响应长度在 OFDM保护间隔之内;再通过CO-OFDM系统相位噪声模型的分析,对信道冲激响应长度 以内的相位噪声进行补偿,进一步提高信道估计的准确性。仿真结果表明,在256个子载波 的CO-OFDM系统中,APNC算法的复乘次数在IRW算法的基础上仅提高0.125倍,在误 码率(BER)为10－4时,APNC 算法对系统光信噪比(OSNR)的要求比IRW算法低了将近0.5dB。