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.

Plane-Pair PEEC Model for Power Distribution Networks With Sub-Meshing Techniques

Abstract: We present an improved plane-pair partial element equivalent circuit (PEEC) model for power distribution network modeling based on the PEEC formulation. The model can include via connections, decoupling capacitor macro-models, and discontinuities such as holes in the plane-pairs. An efficient approximate inductance sub-meshing model is described for large printed circuit plane-pairs with complex geometries and numerous vias. The modified nodal analysis (MNA) used leads to a flexible circuit solution where we can compute inductances, resistances, impedances, or other circuit models, including dc solutions. The MNA equations include effective optimizations such as the placement of capacitors. Today, a large class of methods are available based on numerous formulations including finite-difference time-domain, finite-element method, integral equation model, and cavity models. Each of the approaches has its own type of problems for which it is most suitable.

An Equivalent Circuit Model to Analyze Passive Intermodulation of Loose Contact Coaxial Connectors

Abstract: Loose contact coaxial connectors are significant sources of passive intermodulation (PIM) in high-power and high-frequency communication systems. In this paper, a circuit model is presented to analyze PIM distortion in loose contact coaxial connectors. First, the loose contact surface model is built to calculate metal–insulator–metal and metal–metal contact resistance; and a method of time-domain reflectometry is used to verify the additional impedance of the loose contact surface. Then, the loose contact current is investigated to drive the equivalent circuit model of loose contact coaxial connectors. Finally, a two-tone experimental verification is conducted to show that the PIM of a loose contact coaxial connector can be analyzed by this model.

Analytical Prediction of Crosstalk Among Vias in Multilayer Printed Circuit Boards

Abstract: Crosstalk among vias is a significant problem in high-speed multilayer printed circuit boards (PCBs), deteriorating signal quality and increasing jitter, especially when circuit density is high. In this paper, a two-step via crosstalk evaluation procedure is proposed. A fast approach for crosstalk estimation is developed for net screening as the first step. Then, more accurate but more time-consuming modeling can be performed for critical nets or the problematic nets identified in the screening. The main contribution of this study includes the analytical prediction of crosstalk among vias based on an infinite parallel-plane assumption. Its effectiveness and efficiency to predict the trends in the crosstalk among vias in practical PCB designs are demonstrated.

MoM based current reconstruction using near-field scanning

Abstract: Multiple digital ICs sharing ground plane have potential problems of ground noise interference to each other. Current distribution on the ground plane can introduce intra-system EMC issues, which can possibly result in receiver desensitization issue in wireless devices. In this paper, a method of moment (MoM) based current reconstruction method is proposed to estimate the current on the ground plane. This method requires phased resolved near field data for accurate current reconstruction. The proposed method is validated by a numerical example. The current reconstructed from the proposed method is compared with the current from the simulation tool. The difference is within 3.5 dB which is acceptable for most engineering practice.

Eliminating via-plane coupling using ground vias for high-speed signal transitions

Abstract: When a high-speed signal transits through a via that penetrates a plane pair, parallel-plane resonances can cause additional insertion loss for the signal. To eliminate this via-plane coupling, ground vias are added adjacent to the signal via. This paper discusses the impact of the ground vias as a function of the number of the ground vias, their locations, and the size of the plane pair. A block-by-block physics-based equivalent circuit modeling approach is used in the study. The underlying physics of the phenomenon and the design implications are also discussed in the paper.

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.