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.

Temperature Effects in OTA MIMO Measurement

Abstract: Evaluating transceiver performance in the research and development stage is the basic function of over-the-air (OTA) testing. OTA testing is considered as the standard method for determining the radiated performance of wireless devices. The multiple-input–multiple-output (MIMO) technology used in wireless devices through the integration of multiple antennas is important for the current 4G long-term evolution (LTE) and the future fifth-generation (5G) wireless systems. OTA testing may be the optimal method for MIMO performance evaluation. During MIMO measurement, the transmitting power level of MIMO devices is set to 10 dB lower than the maximum transmitting power level. Because the transmitting power level can affect a device’s physical temperature and, thus, proportionally increase the noise temperature and affect the throughput of the wireless equipment, the MIMO throughput of the device under test (DUT) determined with standard OTA measurement may not reflect real-world usage, and failure to consider the temperature effect of the DUT might contribute to measurement uncertainty. Here, to verify the temperature effect, we modified the radiated two-stage (RTS) procedure for MIMO systems to eliminate this uncertainty and quantify the temperature effect on DUT MIMO throughput. With this proposed method, the measured MIMO performance is a function of the temperature of the DUT, which is determined according to the transmitting power level of the DUT in its thermally stable condition. The proposed method further provides crucial information enabling engineers to optimize functional and EMC designs.

Transmission line modeling of vias in differential signals

Abstract: Signal layer transitions in differential lines are modeled using both FDTD and equivalent circuit methods. The equivalent circuit is developed based on transmission-line reasoning regarding via behavior. Parameters of each transmission-line segment are obtained based on its corresponding physical geometry. The mixed-mode S-parameters from the equivalent circuit and the FDTD modeling are compared. Good agreement is demonstrated in the frequency range from 1 GHz to 20 GHz. The results indicate that vias in differential lines can be modeled as a transmission line for a quick and easy engineering estimation of the differential signal behavior in an environment of signal layer transitions.

Characterizing EMI radiation physics for edge-and broad-side coupled connectors

Abstract: Electromagnetic radiation for a printed circuit board (PCB) midplane connector is studied in this paper. By applying integral-equation (IE) based method and characteristic mode (CM) analysis, the current is split into radiating and non-radiating ones. The radiated power from each part of the structure can be quantified using the radiating current. Therefore, the radiation hot spot can be identified for both edge-side coupled and broad-side coupled connectors. Furthermore, the radiation characteristics for these connectors are compared.

Fast Band-Sweep Total Isotropic Sensitivity Measurement

Abstract: To provide consistent measurements of radio performance in typical complex environments, the total isotropic sensitivity (TIS) is used as a key parameter measured in anechoic chambers. Currently, the TIS measurement is based on the integration of the measured effective isotropic sensitivity at every angle over a spherical surface. This measurement is time consuming so it is only performed for three channels in a band in order to reduce overall measurement time. However, the whole band performance in real environments is critical in the research and development stage, and even in potential certification measurement. A novel fast band-sweep measurement for TIS of wireless devices is proposed in this paper. This method measures the radiated sensitivity and the average gain of the receiver antenna separately, and then combines them to obtain the TIS. The measurement of the radiated sensitivity in a band is efficiently performed based on the relationship between the bit error rate and the received power, and the band-sweep average gain of mobile antennas can be achieved through peak gain measurements. Hence, this method reduces band-sweep measurement time significantly and also ensues the measurement accuracy by eliminating the systematic error in the received signal strength indicator reporting.

Algorithm for Extracting Parameters of the Coupling Capacitance Hysteresis Cycle for TSV Transient Modeling and Robustness Analysis

Abstract: This paper explains the extraction from the measurement of the parameters necessary in time domain to identify the hysteretic behavior of the coupling capacitance of through silicon vias (TSVs). The algorithm was developed in such a way that the equivalent capacitance model can be implemented into standard circuit simulators. A comparison with a known procedure based on the genetic algorithm approach is offered as validation. Results showing the robustness of the algorithm and the effects of the hysteresis on the crosstalk among TSV and integrated circuit active devices are reported and discussed.

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.