Sequential Circuit Test Generation Using a Symbolic/Genetic Hybrid Approach

Symbolic and genetic techniques are combined in a new approach to sequential circuit test generation that uses circuit decomposition, rather than the algorithmic decomposition used in previous hybrid test generators. Symbolic techniques are used to generate test sequences for the control logic, and genetic algorithms are used to generate sequences for the datapath. The combined sequences provide higher fault coverages than those generated by existing deterministic and GA-based test generators, and execution times are significantly lower in many cases.     

FDTD方法分析光子带隙微带结构

本文采用时域有限差分法分析计算了一维光子带隙微带结构的S参数,并设计制作了光子带隙（PBG）微带线,进行了测量。将计算结果与测量结果对比可以看出两者吻合得比较好,说明采用的分析方法是有效的。     

用FDTD分析微带结构过程的优化

本文用3D-FDTD(三维时域有限差分法)计算了微带贴片天线和微带滤波器的S参数.提出了一种新的提取入射场的方式,简化了计算过程,从而提高了计算速度.并将计算结果与MWO软件仿真结果以及实际测量结果进行对比加以验证.     

MEMS层叠式微带贴片天线的FDTD分析

将微机电系统(MEMS)技术应用于射频(RF)领域,制作新型的微带天线,是目前的一个重点和热点.文章以Maxwell方程为出发点,应用时域有限差分(FDTD)法对MEMS层叠式微带贴片天线进行精确的分析,给出了经济实用的近似吸收边界条件,找到了一系列精确模拟微带贴片天线、有效减少存储空间和计算量、节约计算时间的方法.     

降低耦合微带线间串扰问题--FDTD分析

考虑耦合微带线结构的远端串扰问题,用FDTD方法对不同结构的耦合微带线(普通耦合微带线,上方覆盖一层电介质层的耦合微带线,有封装结构的耦合微带线)进行了全波分析后得出结论：在耦合微带线上方覆盖一层电介质层,能降低其远端串扰。     

Modelling and Analysis of Cuk Converter Using Current Injected Equivalent Circuit Approach

The current-injected equivalent-circuit approach has been developed for modelling and analysis of switching dc-dc converters and is very versatile. This approach can also be applied for modelling and analysis of complex converters or cascaded converters. To demonstrate the ability of the current-injected equivalent-circuit approach, the modelling and analysis of a Cuk converter is carried out. A small signal equivalent-circuit model is obtained which represents both input and output properties of the nonlinear converter. The results are presented in the form of linear equivalent-circuit models, as well as transfer functions.     

T型微带线间串扰问题的FDTD分析与抑制

T型微带线的串扰是高速电路信号完整性问题中的重要组成部分。采用PML(Perfectly Matched Layer)-FDTD方法首次对T型微带线间的串扰问题进行全波分析,并给出抑制串扰的具体措施。PML-FDTD仿真结果表明,不同的改进结构参数对串扰的影响不同：(1)开口距离S越大线间串扰越小,最多减小10dB;(2)开口角度 越小线间串扰越小,减小幅度最多达14dB。由此得出,在T型微带线上开三角形口,通过改变开口距离S和开口角度 可实现对邻近微带线串扰的有效抑制。     

对时域有限差分法分析微带贴片天线的某些改进

采用非分裂式理想匹配层(UPML)吸收边界条件有效地减小了计算空间；使用金属细线算法考察了探针半径对微带天线特性的影响；对于输入阻抗及方向图计算中涉及到的晚时响应采用修正的广义函数束方法(GPOF)进行外推插值，大大节省了计算时间，并使用解析方法有效地减少了离散傅立叶变换的计算量；对于采用软激励时时域电压波形不收敛于零的问题提出了一种解决办法；比较了有限大及无限大介质衬底对天线特性的影响。计算结果与现有文献及实验数据相比较，证明了本文方法的正确性和有效性。     

A Broadband Compact Microstrip Rat-Race Hybrid Using a Novel CPW Inverter

A new compact microstrip rat-race hybrid with an octave bandwidth employing a novel frequency-independent coplanar waveguide (CPW) phase inverter is reported in this paper. The 270deg branch of a conventional rat-race is replaced by a -90deg branch, which is realized by a 90deg microstrip line and the CPW phase inverter. A new microstrip-to-CPW transition is introduced for which a lumped-element model is devised to facilitate parameter optimization. The designed transition has an insertion loss less than 0.33 dB across the designed frequency band from 1.5 to 3.5 GHz. The footprint of the proposed design is reduced by 75% and shows almost 60% and 80% enhancements in the 0.5-dB mismatch bandwidth of amplitude and 10deg mismatch bandwidth of phase, respectively, when compared with the conventional implementation. The proposed hybrid can be fabricated using a conventional printed-circuit and plated thru-hole technologies     

A Compact Wide-Band Rat-Race Hybrid Using Microstrip Lines

A compact microstrip rat-race hybrid with a 50% bandwidth employing space-filling curves is reported in this letter. The footprint of the proposed design occupies 31% of the area of the conventional similar design. Across the frequency bandwidth, the maximum amplitude unbalance is 0.5 dB, the phase variation is plusmn5^deg , the isolation is better than 25 dB and the return loss is greater than 10 dB. Moreover, the circuit is planar, easy to design, and consists of only one layer without requiring plated thru holes, slots or bonding wires.     

FDTD结合最小二乘拟合法分析PBG滤波结构

为了能应用FDTD方法快速有效地分析各种PBG滤波结构电磁特性,该文应用FDTD结合最小二乘拟合法对两类新型PBG滤波结构进行了具体分析,给出了FDTD结合最小二乘拟合法计算的最小迭代步数和如何选出谐振段去除振荡原则,最后通过数值仿真结果,表明该方法能有效减少FDTD的迭代步数,节省计算时间,特别适用于大周期和复杂的PBG滤波结构分析。     

MOMTD/FDTD混合法分析线天线与近场媒质的相互作用

采用能够充分发挥MOM与FDTD法各自优势的MOMTD/FDTD混合法,对任意形状线天线与近场媒质的相互作用在时域进行仿真计算。在对MOMTD/FDTD混合法进行验证的基础上,用MOMTD/(FD)2TD混合方法对脉冲电压激励下的线天线与由色散媒质构成的人体头部之间的相互作用进行了仿真研究,计算出了头部的局部比吸收能量分布。     

微带对数周期天线的FDTD分析

应用FDTD方法分析了一种电磁耦合微带对数周期天线的宽频带特性，通过FFT得到天线的阻抗特性、反射损耗及增益等，其结果对实际设计工作具有指导性意义。     

Interdigital Microstrip Circuit Parameters Using Empirical Formulas and Simplified Model

Empirical formulas are given for single- and multiple-coupled microstrips, directly giving propagation mode admittances and phase velocities to be used in simplified expressions for the admittance parameters for the 2N-port network in the form of N-coupled strips, thus forming the basis for both analysis and synthesis of interdigital microstrip circuits. Calculated and measured results are presented for two interdigital band-pass filters synthesized as Chebyshev filters.     

Robust Video Watermarking Using a Hybrid DCT-DWT Approach

In order to solve the limitations of the digital video watermarking algorithm, this paper proposes a new robust video watermarking algorithm using combining discrete cosine transform (DCT) and discrete wavelet transform (DWT) techniques. First of all, the video frames are randomly selected and then the DCT algorithm is applied to the selected video frames. After that, the first column of the selected video frames is scrambled using the Arnold algorithm. Furthermore, every column with 4 direct current (DC) coefficients is reshaped and transformed into four different sub-bands using the DWT technique. Next, the watermark is embedded into the approximation (LL) sub-band. The proposed algorithm is easy to carry out because it provides random frames with no special requirements for video frames. The experiment results indicate that this algorithm can resist against different kinds of watermarking attacks, such as the Gaussian filter attack and sharpen attack. In addition, it also illustrates that the proposed algorithm has a better result than some other watermarking algorithms.     

Parallel Plate Cavity Mode Suppression in Microstrip Circuit Packages Using a Lid of Nails

The suppression of parallel plate and cavity modes in shielded microstrip circuits is presented. To this aim a textured metal lid consisting of periodically located pins known as a bed of nails is employed. The mode suppression has a bandwidth of more than 2:1, and it does not interfere much with the microstrip circuit. Thereby, this mode suppression technique introduces a new advantageous packaging technology for high frequency circuits.      

基于时域有限差分法的微带天线分析

微带天线具有许多优点,在许多领域得到广泛应用。为精确设计微带天线,需了解描述天线性能的电参数。介绍了一种数值分析方法——时域有限差分法（FDTD）,从Maxwell旋度方程出发推导FDTD差分格式计算过程,总结出分析电磁问题的一般步骤,并采用FDTD分析了一款典型的微带天线。和电磁仿真软件XFDTD仿真结果相比较,可以看出FDTD计算结果与软件仿真结果吻合得很好。     

Speeding Up PEEC Partial Inductance Computations Using a QR-Based Algorithm

The partial element equivalent circuit (PEEC) approach has been used in different forms for the computation of equivalent circuit elements for quasi-static and full-wave electromagnetic models. In this paper, we focus on the topic of large scale inductance computations. For many problems as part of PEEC modeling, partial inductances need to be computed to model interactions between a large numbers of objects. These computations can be very time and memory consuming. To date, several techniques have been devised to reduce the memory and time required to compute the partial inductance entities, as well as the time required to use them in a circuit analysis compute step. Some of the existing methods use hierarchical compression while some others are based on issues like properties of the inverse of the partial inductance matrix. However, because of inherent limitations, most of these methods are less suitable for PEEC applications. In this paper, we present an approach which is based on the compression of the partial inductance matrix utilizing the QR decomposition of the far coefficients submatrices. The QR-decomposed form is represented as a compressed SPICE-compatible circuit. This yields an efficient and mathematically consistent approach for reducing the storage and time requirements     

基于P型交指结构的星载微带电路小型化设计

现有星载微波系统中大量使用了各种形式的微带电路,但由于微带电路在低频率时尺寸较大,不利于星载产品小型化,因此提出了一种基于交指结构的微带电路小型化设计方法。该方法采用两个交指电容和高特征阻抗微带线构造的仔型结构替代原有微带结构,从而减小微带电路尺寸。对该方法进行分析并给出了设计理论,进行了仿真及实测验证,并成功应用到多种不同形式的微带电路中。最后给出了两个已验证的实例,一个基于FR4材料的2.4 GHz 功分器和一个基于RO4003C的1.4 GHz 耦合器。该设计方法可以在不改变电性能的基础上减少微带电路约40%的面积。     

耦合微带线间串扰问题的FDTD法分析

在模拟和数字电路中,耦合微带线间的串扰会降低设备的性能。为了降低线间串扰,在攻击线两边各插入了一列用金属填充的、顶端用微带连接的接地孔。利用FDTD方法对该结构进行模拟,给出了接地孔的有效放置方法。