Yansheng Wang

Conducted-emission modeling for a switched-mode power supply (SMPS)

This paper is focused on the construction of a conducted-emission model for a switched-mode power supply (SMPS). First, the total voltage source is extracted by measurement. Second, the coupling path between the aggressor and the victim is characterized by both simulation and measurement. Finally, the coupled noise to the victim with respect to the extracted total voltage source can be obtained by both simulation and calculation. Both results match well with the measurement result, which validates the robustness of the constructed model.

Stochastic modeling of a high-speed signal channel by polynomial chaos method

A stochastic model for a simplified high-speed channel is proposed, which considers six key sources of variations. Based on the model, the polynomial chaos (PC) method is applied to quantify the uncertainties. The effectiveness of the PC method is validated by the Monte Carlo (MC) method. Through the variation analysis, the most significant factor affecting a certain output can be identified, which is useful for the optimization of the channel. Additionally, the model can statistically predict the mean and the standard deviation of the outputs when all the variations take effects.

Variability analysis of crosstalk among pairs of differential vias using polynomial-chaos and design of experiments methods

The variability of the worst-case crosstalk among differential vias in response to the change of the relative locations of the ground and the differential vias are studied in this work. The polynomial-chaos (PC) and the design of experiments (DoE) methods are applied to construct the statistical models. Both methods work well. But the DoE method is preferred in our case since it takes fewer simulations.

Estimating the near field coupling from SMPS circuits to a nearby antenna using dipole moments

In this paper, the near field coupling from SMPS circuits to a nearby antenna is studied using dipole moments [1]. The dipole moments are extracted from scanned H fields on a plane above SMPS circuits, and then imported into an HFSS model to do full wave simulation. The simulated coupling matches well with direct measurement. Methods to resolve magnitude and phase of near fields of SMPS noise source are introduced. Error analysis is included in the end as well.

Studying the effect of drilling uncertainty on signal propagation through vias

A differential via structure with four varying factors are defined in this paper. The Monte Carlo (MC), stochastic collocation (SC) and design of experiments (DoE) methods are employed to quantify the drilling uncertainties in the abovementioned via structure. A comparison of the results shows that the SC method is more robust and can more efficiently and accurately estimate the mean and the standard deviation of the responses, compared to the DoE method.

Differential integrated crosstalk noise (ICN) reduction among multiple differential BGA and Via pairs by using design of experiments (DoE) method

The integrated crosstalk noise (ICN) has been wildly used as an alternative to the insertion crosstalk ratio (ICR) for channel crosstalk evaluation in the IEEE 802.3ba standard. In this work, a differential ICN analysis is performed for several configurations of package-to-PCB transitions. Using the design of experiment (DoE) statistical method, differential ICN is quickly estimated for various input factors such as pin mapping, physical dimensions, and level of shielding. Optimization guide line is proposed to maintain the tradeoff among the differential ICN, design space, and manufacturing cost.

Coupling Analysis for Wires in a Cable Tray Using Circuit Extraction Based on Mixed-Potential Integral Equation Formulation

The China high-speed trains use cable trays to neatly arrange the cables running through the distributed systems. On one hand, they protect cables against external electromagnetic interference and reduce external radiation from the cables. On the other hand, the cable trays create waveguide structures that affect the coupling among cables inside the cable trays. To simplify coupling analysis for cables going through a cable tray, a lumped circuit model was built using admittance blocks extracted from a mixed-potential integral equation (MPIE) formulation. In the MPIE formulation, either the half-free space or the waveguide dyadic Greens function was used depending on the region where the cables were. A test case was investigated. Results by the proposed circuit model were validated by measurement and full-wave simulation results.

Accurate Evaluation of Field Interactions Between Cable Harness and Vehicle Body by a Multiple Scattering Method

Interactions between cable harness and vehicle body can be calculated using the full-wave method-of-moments (MoM) formulation. Although the full-wave MoM formulation can help us to calculate these interactions with great accuracy, it can be fairly time consuming when dealing with complex wire structures. On the other hand, the conventional multiconductor transmission-line theory can be used to obtain a simple model of the interactions, but only the effect of the transmission-line (TL)-mode current can be accounted for in this method. Starting with the complete electrical field integral equations, the current on a two-conductor thin wire structure due to incident field illumination can be decomposed into TL and antenna modes. Both modes can be solved using a SPICE solver in the form of Telegraphers equations. A proposed multiple scattering (MS) method based on a hybrid of TL and surface MoM can then be used to calculate interactions between thin wire structures, such as cable harness, and conductive surfaces, such as vehicle body. A test case shows that wire current computation using the proposed MS method takes less time but reaches the same accuracy compared to the full-wave MoM.

A survey on modeling strategies for high-speed differential Via between two parallel plates

This paper presents a survey on physics-based modeling strategies for differential via in high-speed multilayer printed circuits (PCBs). Driven by the goals of accurate and efficient design, researchers have explored several approaches for differential via modeling, include π-type RLC circuit, differential transmission line with via-plate capacitance/effective dielectric constant and parallel plate impedance model. This survey provides overviews of these modeling strategies and comparisons by correlating mixed-mode S-parameter from HFSS. In particular, this paper then aims on building a generic parameterized and SPICE-compatible circuit model for designing differential via in a frequency range up to 40GHz.

Studying the effects of location offset on the evaluation of MIMO performance based on the radiated two-stage (RTS) method

The intermediate results in Stage I of the RTS method can be used to help evaluate the quality of the designed MIMO antennas, which can benefit engineers with the debugging process for MIMO systems. This is achieved by exploiting the obtained intermediate results to calculate some metrics including envelope correlation coefficient (ECC) and antenna gain imbalance (AGI). The detailed process is described in the paper. The performance evaluation is desired to be accurate. However, the user equipment (UE) location offset may exist during real measurements and this can affect the evaluation of the MIMO performance. Thus, it is of interest to study to what extent the MIMO performance evaluation is influenced by the UE location offset.