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.

Stub length prediction for back-drilled vias using a fast via tool

Abstract: This paper presents a fast via tool to predict the via stub length after back-drilling. The fast via tool is developed associated with the physics based via model and is combined with the calculation of plane impedance and via capacitance block by block. The entire via model is built by connecting those via blocks one after another accordingly. The plane impedance is calculated from an analytical formula and the via capacitance is computed from the point of view of energy by solving the potential distribution on each via block using FEM. Via stub length is predicted with the observation of strong resonant trough on the insertion loss, which can be in single-ended mode or mixed mode. Two cases, one signal via surrounded by eight ground vias and four signal vias surrounded by four ground vias, are used to verify the modelling accuracy of the fast via tool by correlating to the measurements. The third case is about via stub length extraction as well as the sensitivity investigation between the stub length and the resonant frequency.

Study of TDR Impedance for Better Analysis to Measurement Correlation

Abstract: SI engineers usually build PCB test coupons and perform cross-sectioning and material properties extraction, and then do design optimization. But designing transmission lines on PCB with good analysis to measurement correlation is really challenging. Although there are some systematic approaches which can be applied to a broad range of applications for highspeed digital designs, it is found that in the validation process, there is always several-ohm mismatch in the comparison of TDR impedance between simulated and measurement results. This degrades engineers' confidence about high-speed design. Taking a real case as an example, this paper is trying to analyze which factors have influence on the trace impedance correlation and showing step by step how the agreement can be improved.

Optimizing decoupling capacitor placement to reduce effective inductance

Abstract: Optimizing decoupling capacitor placement to insure rapid charge delivery is discussed in this paper. Placing additional decoupling capacitors in close proximity may reduce effective inductance but this inductance is only reduced under certain conditions.

Capacitance Calculation for Via Structures Using an Integral Equation Method Based on Partial Capacitance

Abstract: In this paper, a new integral equation formulation for via structures is developed for the capacitance extraction between vias and planes. The formulation is initially developed for axially symmetric geometries and then extended to axially asymmetric geometries by changing the circular ring cells to arc cells. The extended method can be used to calculate the shared-antipad via structure, which is widely used in high-speed differential signal interconnects. In addition, the image theory is used to handle inhomogeneous media, and a new technique is given to reduce computational costs for via-to-plane structures based on properties of the capacitance-matrix elements. The proposed method is validated with a commercial finite element method-based tool for several practical via structures. The extracted capacitance is also incorporated into the physics-based via model and validated with full-wave simulations.

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.