Jun Fan

Bio: Jun Fan is an academic researcher from Missouri University of Science and Technology. The author has contributed to research in topics: Equivalent circuit & Printed circuit board. The author has an hindex of 36, co-authored 482 publications receiving 5641 citations. Previous affiliations of Jun Fan include Ulsan National Institute of Science and Technology & University of Missouri.

Limitations of First-Order Surface Impedance Boundary Condition and Its Effect on 2D Simulations for PCB Transmission Lines

Abstract: Signal integrity (SI) issue is a critical concern as the data rate continues to increase and SI analysis is heavily dependent on simulations. Inaccurate simulation data may result in inadequate design decisions influencing high-speed digital design and optimization. The surface impedance boundary condition (SIBC) concept is generally utilized in commercial electromagnetic (EM) solvers, which is considered to be an efficient technique as the interior region of the conductor of interest does not need to be included in the numerical procedure. The first-order SIBC has been incorporated into many EM simulation tools widely used in industries. In this paper, the limitations of the first-order SIBC in 2D simulations for PCB transmission lines are analyzed and demonstarted for the first time. Different PCB transmission lines with various cross-sectional geometries are simulated in a commercial 2D EM solver with and without the implementation of the first-order SIBC to reveal the effect on the simulated transmission line behaviors. It is found that the accuracy of the simulations with the first-order SIBC decreases as the edge of the signal conductor in the cross-section becomes narrower. The possible solutions are proposed to overcome the issue.

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

Abstract: 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.

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

Abstract: 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.

Modeling and analysis of a trace referenced to a meshed ground plane

Abstract: Meshed planes are used in today's flexible PCB designs, and due to their non-homogeneous nature, Modeling of nearby interconnects increases in complexity. In this paper, a method to evaluate the effective characteristic impedance of a trace referenced to a meshed plane is proposed that is simpler and optimization based. The effective impedance and the per-unit-length parameters of the line were associated with the meshed plane periodical patterns as well as trace relative locations. A systematic study was performed to reveal the essential relationship between the meshed plane geometric parameters and the trace characteristics.

The effects of via transitions on differential signals

Abstract: Vias in differential transmission lines have been modeled using the finite-difference time-domain (FDTD) method. The velocity that the differential signal propagated through the vias was estimated. Differential S-parameters were calculated up to 50 GHz. Below 10 GHz, the differential signal can propagate through vias without much reflection and distortion. However, as frequency increases, the reflection from the vias and the loss of differential power become significant.

I and i

Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

IEEE Transactions on Microwave Theory and Techniques and Antennas and Propagation Announce a Joint Special Issue on Ultra-Wideband (UWB) Technology

Abstract: Before the emergence of ultra-wideband (UWB) radios, widely used wireless communications were based on sinusoidal carriers, and impulse technologies were employed only in specific applications (e.g. radar). In 2002, the Federal Communication Commission (FCC) allowed unlicensed operation between 3.1–10.6 GHz for UWB communication, using a wideband signal format with a low EIRP level (−41.3dBm/MHz). UWB communication systems then emerged as an alternative to narrowband systems and significant effort in this area has been invested at the regulatory, commercial, and research levels.