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Author

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.


Papers
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Journal ArticleDOI
TL;DR: In this paper, closed-form expressions for transient power distribution network (PDN) noise caused by an IC switching current are derived for a PDN structure comprised of traces with decoupling capacitors.
Abstract: Closed-form expressions for transient power distribution network (PDN) noise caused by an IC switching current are derived for a PDN structure comprised of traces with decoupling capacitors. Criteria for identifying a dominant decoupling capacitor for an impulse switching current are also proposed. The derived PDN noise expressions are validated with measurements of currents at both local and bulk capacitors, the PDN impedance, and the total voltage noise in an operating consumer device.

41 citations

Journal ArticleDOI
TL;DR: A new machine learning based source reconstruction method is developed to extract the equivalent dipole moments more accurately and reliably and is believed to have a better accuracy.
Abstract: In radio frequency interference study, equivalent dipole moments are widely used to reconstruct real radiation noise sources. Previous reconstruction methods, such as least square method (LSQ) and optimization method are affected by parameter selections, such as number and locations of dipole moments and choices of initial values. In this paper, a new machine learning based source reconstruction method is developed to extract the equivalent dipole moments more accurately and reliably. Based on the near-field patterns, the proposed method can determine the minimal number of dipole moments and their corresponding locations. Furthermore, the magnitude and phase for each dipole moment can be extracted. The proposed method can extract the dominant dipole moments for the unknown noise sources one by one. The proposed method is applied to a few theoretical examples first. The measurement validation using a test board and a practical cellphone are also given. Compared to the conventional LSQ method, the proposed machine learning based method is believed to have a better accuracy. Also, it is more reliable in handling noise in practical applications.

40 citations

Proceedings ArticleDOI
02 Aug 1999
TL;DR: In this article, the power island concept is investigated experimentally, to determine its noise mitigation attributes and limitations, and a modeling approach that is suitable for arbitrary PCB island geometries including lumped SMT decoupling capacitors is also presented.
Abstract: Power island structures are often employed for minimizing the propagation of high-frequency noise on DC power buses. The rationale is based on introducing a series impedance in the power plane to provide isolation of a noise source from the rest of the PCB design. The power island concept is investigated herein experimentally, to determine its noise mitigation attributes and limitations. A modeling approach that is suitable for arbitrary PCB island geometries including lumped SMT decoupling capacitors is also presented. The modeling and measurements indicate that island structures can achieve some degree of isolation under certain conditions.

39 citations

Journal ArticleDOI
TL;DR: In this article, a high-sensitivity resonant electric field probe was designed, consisting of an LC resonator loaded by quarter-wave transformers for optimal power transfer at the resonant frequency.
Abstract: Near-field probes with high sensitivity facilitate the identification of the root causes of intrasystem radio frequency interference issues, where weak noise desensitizes the receiver. In the study presented in this paper, a high-sensitivity resonant electric field probe was designed, consisting of an LC resonator loaded by quarter-wave transformers for optimal power transfer at the resonant frequency. Based on the equivalent circuit model, analytical derivations and numerical simulations were performed to illustrate the design methodology. The simulation results agreed well with the measured values. At the resonant frequency of 1.577 GHz, the measured $\vert S_{21}\vert$ from a matched trace to the resonant probe was approximately 6.6 dB higher than that of an equivalently sized broadband probe.

36 citations

Journal ArticleDOI
TL;DR: In this paper, a multiband dual-polarized omnidirectional antenna for 2G/3G/Long Term Evolution (LTE) mobile communications is proposed, which consists of horizontal polarization (HP) and vertical polarization (VP) element with separate feeds.
Abstract: A multiband dual-polarized omnidirectional antenna for 2G/3G/Long Term Evolution (LTE) mobile communications is proposed in this letter, which consists of horizontal polarization (HP) and vertical polarization (VP) element with separate feeds. The VP element consists of three polygonal radiation patches with three equally spaced legs shorted to the ground plane. The HP element consists of three wideband slot loop structures, which is nested on the top of the VP element. Three slot loop structures provide a 360° coverage for HP and enhance its bandwidth. Both the simulated and measured results indicate that the frequency bands of 1650–2900 MHz for HP and 780–2700 MHz for VP can be achieved. The reflection of VP improves the gain of the HP element at least 1 dBi after nesting. The gain of HP element is more than 3 dBi for LTE, and the gain of VP element is more than 5 dBi in the LTE band and 1.5 dBi in the 2G band. Port isolation larger than 30 dB and low-gain variation levels are also obtained. The proposed antenna can be applied in mobile communications.

35 citations


Cited by
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Journal ArticleDOI

[...]

08 Dec 2001-BMJ
TL;DR: There is, I think, something ethereal about i —the square root of minus one, which seems an odd beast at that time—an intruder hovering on the edge of reality.
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 …

33,785 citations

01 Jan 2016

733 citations

Journal ArticleDOI
TL;DR: In this paper, the authors proposed a wideband ultra wideband (UWB) communication protocol with a low EIRP level (−41.3dBm/MHz) for unlicensed operation between 3.1 and 10.6 GHz.
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.

452 citations