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.

Capacitance Calculation for Offset Via Structures Using an Integral Approximation Approach Based on Finite Element Method

Abstract: A simple yet efficient approach is presented to extract the via-plane capacitances for an offset via structure. According to the integral approximation approach, the geometry of offset via is first divided into several segments with equally distributed angles from the origin. The two-dimensional FEM method for the concentric case is used for each segment based on its pad-stack parameters. Then, the final offset via-plane capacitance is approximated as the average of these ‘segmental’ capacitance values. Numerical examples demonstrated that the combined method has similar accuracy with a three-dimensional solver but it has much higher efficiency in both CPU time and memory cost.

Insertion Loss Reduction Using Rounded Corners to Mitigate Surface Roughness Effect in PCB Transmission Lines

Abstract: Signal integrity (SI) can be interpreted as a measure of the distortion of the incident pulse, which is attributed to various contributors, e.g., inter-symbol interference (ISI), crosstalk, jitter, etc. The channel insertion loss is generally the most critical concern in SI designs, since it determines the working bandwidth of a high-speed channel, and the bandlimited channels are known as the root cause of ISI. At the tens of Gigabit rates in use today, PCB transmission lines may have appreciable losses, which can be divided into frequency-dependent dielectric loss and conductor loss, and noticeable amount of losses can be generated at high-frequencies due to the skin effect and copper rough surfaces. In order to reduce the additional conductor loss due to the surface roughness, the employment of low-profile copper foils is a common practice in high-speed digital design. However, this existing method is not cost-effective. In this paper, insertion loss reduction using rounded corners are proposed and verified using both 2D and 3D full-wave simulations for the first time. Rounded corners can mitigate the increased insertion loss due to copper surface roughness in PCB transmission lines, and can be applied in high-speed interconnect designs to increase eye margins. The impact of applying rounded corners on far-end crosstalk is also discussed.

Modeling shared-via decoupling in a multi-layer structure using the CEMPIE approach

Abstract: The CEMPIE approach, a circuit extraction technique based on a mixed-potential integral equation, has been applied to model multi-layer structures including power and signal layers. Power-bus noise mitigation effects due to a decoupling capacitor were studied for several cases with different spacing between the capacitor and an integrated circuit (IC). Modeling results indicate that the capacitor sharing a common via with the IC power/ground pins is superior; viz., it results in the lowest power-bus noise under similar conditions.

Statistical estimation of root mean square crosstalk in SFP+ cable evaluations

Abstract: A rigorous statistical estimation of the root mean square equation is proposed for near-end crosstalk simulation in SFP+ cable evaluations. This method employs the pulse response, the near-end output in the victim pair due to a single-pulse input of one bit long in the aggressor pair. This pulse response can be obtained from vector network analyzer (VNA) measurements. Thus SFP+ cable evaluations can be effectively performed using easier and more accurate frequency-domain measurements, instead of the time-domain ones defined in the specification.

Efficient DC and AC Impedance Calculation for Arbitrary-Shape and Multilayer PDN Using Boundary Integration

Abstract: This article presents an efficient methodology based on boundary integration to calculate the dc and ac impedance of power distribution networks (PDNs) for arbitrary-shape and multilayer printed circuit boards (PCBs). The proposed method adopts a boundary element method to extract inductances for the arbitrary parallel-plane shapes. Subsequently, the equivalent circuit formed by the via inductances and plane capacitances is solved using the node voltage method. By merging the parallel and serial inductances and simplifying the equivalent circuit, the computation time can be significantly reduced for a large number of vias and layers. This matrix manipulation strategy can be applied to various PCB structures without human intervention or commercial circuit solvers. Moreover, a contour integral method is employed to calculate the dc resistances for arbitrary shape and multilayer PDNs. Therefore, the wideband PDN impedance from dc to ac frequencies can be efficiently calculated through 1-D boundary integration, which can be performed more quickly than full-wave simulations. The proposed method can aid in the development of electronic design automation tools for PDN design.

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.