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.

Effect of Narrow Power Fills on PCB PDN Noise

Abstract: The printed circuit board (PCB) power delivery network (PDN) performance has become critical with the reducing margins on power noise. This paper deals with a specific question about the size of the power area fill used to route the power current from the dc regulator to integrated circuit(IC), and also used for connecting to the decoupling capacitors. With increased PCB real estate costs, narrow power fills are required, which results in an increase in the connection inductance of decoupling capacitors. This paper uses a proven lumped circuit model extraction procedure, based on the first principle resonant cavity model, to demonstrate the effect of narrow and wide area fills used in typical PCB PDN designs. The frequency domain results thus obtained are used with typical IC current draw profiles to show the impact on the noise voltage developed at the IC. Some design guidelines and conclusions are drawn from these results.

SNR Analysis and Optimization in Near-Field Scanning and EMI Applications

Abstract: In a near-field scanning system, each element of the measurement chain contributes to the thermal noise power density: probe, cables, amplifiers, and the measuring instrument. The signal-to-noise ratio (SNR) is strongly affected by the source output impedance, source temperature, the lossy transmission lines between probe and amplifiers, amplifier noise, amplifier temperature, and amplifier gain. By minimizing the loss between the probe and by using ultralow-noise amplifiers (noise figure (NF) 10 dB, compared to a setup using a 1-m cable and a 3-dB NF amplifier. A resonant probe that is cooled with liquid nitrogen improves measurement SNR by an additional 10–12 dB, as compared to a broadband probe of similar loop size. To combine the advantages of a resonant probe, without sacrificing the ability to measure broadband, a proof of concept is demonstrated that uses a tunable resonant probe which is synchronized to the frequency sweep of the spectrum analyzer.

Investigation and Mitigation of Radio Frequency Interference Caused by Weak Grounding of USB Type-C Receptacle Connector

Abstract: In modern mobile electronic systems, USB connector has been identified as one of the dominant noise sources for desense issues. In this paper, the noise coupled to the Wi-Fi antenna from a USB connector is investigated. With the assistance of full-wave simulations, the root cause of desense noise is identified as the non-ideal electrical connection between the metal chassis and the USB receptacle shell where it is installed. The proposed radiation mechanism is validated through measurements of a real tablet device, and 15 dB noise level reduction is observed with a better grounding structure.

Estimating the via-plane capacitance for differential vias with shared-antipad based on analytical equations

Abstract: Shared-antipad via structure is commonly used for high-speed printed circuit board (PCB) design. Therefore, an accurate via-plane capacitance evaluation for this kind of geometry is critical to facilitate engineering design. In this paper, the analytical equation of via-plane capacitance for separated-antipad via structure is extended to the shared-antipad via structure case, by using the equivalent area of antipad and ratio revision method. The proposed method is validated with numerical methods in HFSS for a typical structure widely used in practical high-speed PCB design.

Stochastic Modeling of a High-Speed Signal Channel By Polynomial Chaos Method

Abstract: 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.

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.