Incorporating Two-Port Networks with S-Parameters into FDTD

A modeling approach for incorporating a two-port network with S-parameters in the finite-difference time-domain (FDTD) method is reported in this paper. The proposed method utilizes the time-domain Y-parameters to describe the network characteristics, and incorporates the Y-parameters into the FDTD algorithm. The generalized pencil-of-function (GPOF) technique is applied to improve the memory efficiency of this algorithm by generating a complex exponential series for the Y-parameters and using recursive convolution in the FDTD updating equations. A modeling example is given, which shows that this approach is effective and accurate. This modeling technique can be extended for incorporating any number of N-port networks in the FDTD modeling

FDTD Modeling Incorporating a Two-Port Network for I/O Line EMI Filtering Design

Electromagnetic interference (EMI) filters are often utilized on I/O lines to reduce high-frequency noise form being conducted off the printed circuit board (PCB) and causing EMI problems. The filtering performance is often compromised at high frequencies due to parasitics associated with the filter itself, or the PCB layout and interconnects. Finite difference time domain (FDTD) modeling can be used to quantify the effect of PCB layout and interconnects, as well as filter type, on the EMI performance of I/O line filtering. FDTD modeling of a T-type and π-type filter consisting of surface-mount ferrites and capacitors is considered herein. The FDTD method is applied to model PCB layout and interconnect features, as well as the lumped element components, including the nonlinear characteristics of ferrite surface-mount parts. The EMI filters with ferrites are included in the modeling by incorporating the time-domain Y-parameters of the two-port network into the FDTD time-marching equations. Good agreement between the FDTD modeling and S-parameter measurements supports the new FDTD algorithm for incorporating two-port networks

Investigation of PCB Layout Parasitics in EMI Filtering of I/O Lines

EMI filters are often utilized on I/O lines to reduce high-frequency noise from being conducted or coupled off the PCB and resulting in an EMI problem. However, layout parasitics are usually inevitable in practical circuit design, and the filtering performance may vary. In this study, the impact of the board layout on the filtering performance is investigated by |S21| measurements of sample PCB boards with different filter layouts. The finite-difference time-domain method is applied to model the boards, support the experimental work, and can be used to provide a means for conducting what-if engineering studies

Representation of Gyromagnetic Composite Media for FDTD Modeling

A composite media containing particles with a high internal field of magnetic anisotropy (hexagonal ferrites) useful for numerous EMC applications in a wide frequency band is considered. Effective constitutive parameters of a high-loss composite gyromagnetic media are represented in the Lorentzian form. It is convenient for the numerical analysis using the finite-difference time-domain (FDTD) algorithm with a recursive convolution procedure. The equations for the electric and magnetic field updating in such media are represented

A Common-Mode Current Measurement Technique for EMI Performance Evaluation of PCB Structures

An experimental technique that measures the common-mode current on a cable attached to a DUT for assessing EMI performance is introduced herein. The technique was applied to evaluate the EMI performance of a module-on-backplane configuration with different connectors and different connector pin-outs

DC Power Bus Design with FDTD Modeling Including a Dispersive Media

DC power-bus modeling in high-speed digital design using the FDTD method is reported here. The dispersive medium is approximated by a Debye model to account for the loss. A wide band frequency response (100 MHz-5 GHz) is obtained through a single FDTD simulation. Favorable agreement is achieved between the modeled and measured results for a typical DC power-bus structure with multiple SMT decoupling capacitors mounted on the board. The FDTD tool is then applied to investigate the effects of local decoupling on a DC power-bus. The modeled results agree with the results from another modeling tool, the CEMPIE (a circuit extraction approach based on a mixed-potential integral equation formulation) method

High-Performance Inter-PCB Connectors: Analysis of EMI Characteristics

Electromagnetic interference (EMI) coupling associated with inter-board connection is investigated. Two experimental techniques, based on |S21| measurements, including both common-mode current and near-field measurements, are reported. Both methods, as well as finite difference time domain (FDTD) modeling, were used as experimental and numerical tools for inter-printed-circuit-board (inter-PCB) connector evaluation. The EMI performance of a lab-constructed stacked-card connector, and a commercially available module-on-backplane connector were studied. EMI characteristics of the connectors are demonstrated by investigating a few aspects of the design: type of shield/ground blade for signal return, number and length of ground pins, signal pin designation, etc. Good agreement is achieved between the measurements and the FDTD modeled results

Feature selection with interactions in logistic regression models using multivariate synergies for a GWAS application

Abstract Background Genotype-phenotype association has been one of the long-standing problems in bioinformatics. Identifying both the marginal and epistatic effects among genetic markers, such as Single Nucleotide Polymorphisms (SNPs), has been extensively integrated in Genome-Wide Association Studies (GWAS) to help derive “causal” genetic risk factors and their interactions, which play critical roles in life and disease systems. Identifying “synergistic” interactions with respect to the outcome of interest can help accurate phenotypic prediction and understand the underlying mechanism of system behavior. Many statistical measures for estimating synergistic interactions have been proposed in the literature for such a purpose. However, except for empirical performance, there is still no theoretical analysis on the power and limitation of these synergistic interaction measures. Results In this paper, it is shown that the existing information-theoretic multivariate synergy depends on a small subset of the interaction parameters in the model, sometimes on only one interaction parameter. In addition, an adjusted version of multivariate synergy is proposed as a new measure to estimate the interactive effects, with experiments conducted over both simulated data sets and a real-world GWAS data set to show the effectiveness. Conclusions We provide rigorous theoretical analysis and empirical evidence on why the information-theoretic multivariate synergy helps with identifying genetic risk factors via synergistic interactions. We further establish the rigorous sample complexity analysis on detecting interactive effects, confirmed by both simulated and real-world data sets.https://deepblue.lib.umich.edu/bitstream/2027.42/142802/1/12864_2018_Article_4552.pd

EMI Resulting from a Signal Via Transition Through DC Power Bus-Effectiveness of Focal SMT Decoupling

Signal vias are commonly used in multilayer printed circuit board (PCB) design. For a signal via transitioning through the internal power and ground planes, the return current has to jump from one reference plane to another reference plane. The discontinuity of the return current at the via excites the power and ground planes, and results in power bus noise, and can produce an EMI problem as well. Numerical methods, such as finite-difference time-domain (FDTD), moment methods (MoM), and partial element equivalent circuit (PEEC), were employed herein to study this problem. The modeled results were supported by the measurements. In addition, the EMI mitigation approach of adding decoupling capacitors was investigated with the FDTD method

Modeling EMI Resulting from a Signal Via Transition Through Power/Ground Layers

Signal transitioning through layers on vias are very common in multi-layer printed circuit board (PCB) design. For a signal via transitioning through the internal power and ground planes, the return current must switch from one reference plane to another reference plane. The discontinuity of the return current at the via excites the power and ground planes, and results in noise on the power bus that can lead to signal integrity, as well as EMI problems. Numerical methods, such as the finite-difference time-domain (FDTD), Moment of Methods (MoM), and partial element equivalent circuit (PEEC) method, were employed herein to study this problem. The modeled results are supported by measurements. In addition, a common EMI mitigation approach of adding a decoupling capacitor was investigated with the FDTD method