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.

Analysis of noise coupling from printed circuit board to shielding enclosure

Abstract: The power distribution network in a printed circuit board (PCB) inside a compact-size enclosure is an effective path for high-speed digital noise to be coupled to the RF receivers inside the same enclosure, causing RF interference (RFI) issues. This noise coupling mechanism from PCB to shielding enclosure is investigated in this paper using the cavity model and the segmentation technique. In this approach, the structure of an enclosure with a PCB inside is divided into cavities with both horizontal and vertical connections. Modeling result agrees well with full wave simulations, and the simulation time is considerably reduced. Furthermore, the relationship among the noise coupling, the PCB-related resonances, and the enclosure-related resonances is studied as well.

Stable recursive convolution for channel response calculation with causality enforcement

Abstract: Checking and enforcing causality of simulated or measured system data is a crucial step for obtaining valid results. Previously, several methods for both frequency and time domain have been proposed. This paper explores the time domain causality enforcement method, its effect on the frequency domain transfer function, and proposes modification of the recursive convolution algorithm for impulse responses with time domain enforced causality to ensure calculation stability.

Dielectric Material and Foil Surface Roughness Properties Extraction Based on Single-ended Measurements and Phase Constant ( $\beta$ ) Fitting

Abstract: Dielectric substrate and foil surface roughness properties of fabricated printed circuit boards (PCB) are important for high-speed channel design. Several stripline-based extraction methods have been developed to characterize dielectric relative permittivity ( $\varepsilon_{r}$ ), dielectric dissipation factor ( $\text{tan}\delta$ ), and foil surface roughness correction factor ( $K_{R}$ ) using measured S-parameters. However, the $\text{tan}\delta$ extraction still needs further improvement due to the difficulty in separation of dielectric and conductor loss. The authors found that the frequency-dependence of the stripline phase constant ( $\beta$ ) is helpful to determine the $\text{tan}\delta$ without introducing high sensitivity to foil surface roughness. By introducing a causal dielectric frequency-dependent model, $\varepsilon_{r}$ and $\text{tan}\delta$ are extracted by fitting measured $\beta$ . The foil surface roughness property (correction factor $K_{R}$ ) is obtained using the conductor loss calculated by subtracting extracted dielectric loss from the total loss. To demonstrate the feasibility of the proposed method examples are provided using simulation data and fabricated PCB.

MIMO Performance Diagnosis Based on the Radiated Two-Stage (RTS) Method

Abstract: A MIMO system on the receiver side includes two major parts: the antennas and the receivers. Traditional MIMO throughput test evaluates performance of the whole MIMO system on the receiver side, but doesn't reveal any insight on the quality of the MIMO antennas and receivers. Later, test methods are developed based on the RTS method to evaluate MIMO antennas and receivers. However, a complete test flow to diagnose the performance of MIMO antennas and receivers is not yet established. Therefore, in this paper a workflow based on the RTS method is proposed to diagnose MIMO antenna designs and facilitate desense debugging. A test case of a real product is given to validate the workflow.

Root Cause Analysis for the Phase Noise of the Clock Generator

Abstract: The performance of the high-speed links in the electronic system is highly dependent on the quality of the clock signal, which can be quantified by phase noise. The phase noise represents the instabilities of the signal in the frequency domain by measuring the power at various offsets from the carrier frequency. The root cause for the phase noise of the clock output at the resonance frequency is analyzed and identified in this paper. The power supply, the heat sink, and the external crystal are the main sources of the phase noise. Spurious occurs at the frequency of the power rail in the measured phase noise. The heat sink over the chip induces the conductive coupling noise to the clock. The low-frequency bump in the phase noise plot turns out to be induced by the external crystal design of the clock. More attention should be paid to the ground routing of the external crystal to ensure the quality of the clock output.

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.