Magnetotransport Properties Of Dirac Semimetal Taco2te2 And Ferromagnetic Weyl Semimetal Co3sn2s2,
2024
Northern Illinois University
Magnetotransport Properties Of Dirac Semimetal Taco2te2 And Ferromagnetic Weyl Semimetal Co3sn2s2, Samuel Pate
Graduate Research Theses & Dissertations
This dissertation investigates the magnetotransport properties of topological semimetals, specifically focusing on the Dirac semimetal TaCo2Te2 and the Weyl semimetal Co3Sn2S2. In TaCo2Te2, I observed extremely large magnetoresistance that violates Kohler’s rule. Extended Kohler’s rule can be applied with a calculation of Hall factor at low temperatures. I also explored the applicability of the two-band and four-band models of carrier analysis and correlate the region where Kohler’s rule is obeyed to the four-band model. In Co3Sn2S2, I explored the angle-dependent anomalous Hall effect (AHE) near the Kagome plane, revealing a tunable AHE under applied fields and an abrupt disappearance of …
Design And Fabrication Of Quantum Cascade Laser Tree Arrays,
2024
University of Central Florida
Design And Fabrication Of Quantum Cascade Laser Tree Arrays, Luke Milbocker
Graduate Thesis and Dissertation 2023-2024
Quantum cascade lasers (QCLs) are semiconductor lasers that can be designed to emit over a very broad wavelength range from the mid-wave infrared (MWIR) to terahertz frequencies. Their compact size and ability to output several watts of MWIR or long-wave infrared (LWIR) radiation makes them ideal sources for directional infrared counter measures (DIRCM). This application is fueling demand for ever more powerful QCLs, but power gains from single QCLs have largely stagnated in recent years. Novel waveguide geometries such as tree-arrays seek to increase output power delivered in a single high-quality beam. InGaAs/AlInAs tree array QCLs based on ridge waveguides …
Enhancing The Bandwidth And Radiation Characteristics Of Size-Reduced Antennas,
2024
Georgia Southern University
Enhancing The Bandwidth And Radiation Characteristics Of Size-Reduced Antennas, Jack P. Nemec
College of Graduate Studies: Theses & Dissertations
Electrically small antennas are researched heavily throughout electromagnetic literature due to their practicality. Antennas need to be able to fit into small places such as cell phones. However, the reduction of antenna size comes at a cost in decreasing the impedance bandwidth and radiation efficiency of the antenna. This research aims to find solutions to having sized-reduced antennas while enhancing both the impedance bandwidth and radiation characteristics of the antenna. First, the size reduction of a dual-element dipole is analyzed. Dual-element dipoles are known to have impedance bandwidth enhancing properties along with the ability to have different radiation modes. Next, …
Radiated Emission Modeling Of A Wireless Power Transfer System,
2024
Missouri University of Science and Technology
Radiated Emission Modeling Of A Wireless Power Transfer System, Hanyu Zhang, Guanghua Li, Viswa Pilla, Chulsoon Hwang
Electrical and Computer Engineering Faculty Research & Creative Works
A radiated emission (RE) model of a wireless power transfer (WPT) system is proposed in this paper to help designers predict, analyze, and mitigate the RE issues during the design process. The proposed model employs both full-wave simulation and circuit simulation to derive a transfer function. Subsequently, it predicts the emission level by combining the transfer function with the measured transmitter waveform through a straightforward calculation. The predicted emissions match the measured RE peaks well up to 300 MHz, with the error within 3 dB. The impact of functional parameters, such as load and coil gap distance, is analyzed based …
A Method For Measuring The Transfer Function Inside A Compact Metallic Enclosure Using A Slot Antenna,
2024
Missouri University of Science and Technology
A Method For Measuring The Transfer Function Inside A Compact Metallic Enclosure Using A Slot Antenna, Xiangrui Su, Wenchang Huang, Junghee Cho, Joonki Paek, Chulsoon Hwang
Electrical and Computer Engineering Faculty Research & Creative Works
Radio frequency desensitization issues comprise two components: noise radiation sources and the transfer function from noise sources to the victim antenna. For modern electronic products, noise sources are often located inside a compact metal enclosure, making it difficult to measure the transfer function using conventional methods. Moreover, opening the metallic enclosure would dramatically change the transfer function, and inserting a near-field probe into the enclosure is challenging and may not even be possible because of the limited space inside. In this article, a novel practical method for measuring the transfer function inside a compact metallic enclosure is proposed and experimentally …
Vertical Interconnect Technology In Silicon, Package, And Printed Circuit Board (Pcb) With Coaxial Structure,
2024
Missouri University of Science and Technology
Vertical Interconnect Technology In Silicon, Package, And Printed Circuit Board (Pcb) With Coaxial Structure, Junyong Park, Chaofeng Li, Eddie Mok, Joe Dickson, Joan Tourne, Donghyun Kim
Electrical and Computer Engineering Faculty Research & Creative Works
This paper introduces vertical interconnect technology in silicon, package, and printed circuit board (PCB) levels with a coaxial structure, respectively. The coaxial structure has been known to be advantageous in terms of signal integrity (SI) compared to the non-coaxial structure. The coaxial structure is easy to control the characteristic impedance Z0 and robust to crosstalk. The silicon-level interconnect includes the wire bonding (WB) and through-silicon via (TSV) technology, the package-level interconnect includes an elastomer package test socket. The PCB-level interconnect includes the vias, and vertical conductive structure (VeCS). For each level, the non-coaxial and coaxial interconnects are compared with the …
Novel Formulation For Generalization Of Mixed-Mode S-Parameters For Coupled Differential High-Speed Digital Channels,
2024
Missouri University of Science and Technology
Novel Formulation For Generalization Of Mixed-Mode S-Parameters For Coupled Differential High-Speed Digital Channels, Manish K. Mathew, Kevin Cai, Chaofeng Li, Mehdi Mousavi, Shameem Ahmed, Donghyun Kim
Electrical and Computer Engineering Faculty Research & Creative Works
As the demand for higher data rates intensifies, achieving accurate S-parameter calculation becomes increasingly critical. The conventional single-ended to mixed-mode S-parameter conversion formulation assumes uncoupled structures, which may not be true for high-speed digital channels. This work introduces a novel, generalized formulation for mixed-mode S-parameters and their corresponding transformation matrices [M1] and [M2], enabling comprehensive analysis of multi-pair coupled differential traces. An intra-pair crosstalk analysis of a tightly coupled strip line and microstrip line verifies and highlights the difference between the proposed and old formulations. A loosely coupled case is analyzed as an additional validation of the proposed formulation. Finally, …
Design Of The Tm010 Mode Cylindrical Cavity Resonator For Pcb Dielectric Characterization,
2024
Missouri University of Science and Technology
Design Of The Tm010 Mode Cylindrical Cavity Resonator For Pcb Dielectric Characterization, Reza Asadi, Chaofeng Li, Seyedmehdi Mousavi, Seyed Moastafa Mousavi, Reza Vahdani, Xiaoning Ye, Donghyun Kim
Electrical and Computer Engineering Faculty Research & Creative Works
This paper presents the study of the TM010 mode cylindrical resonator, which can be used for printed circuit board (PCB) material properties extraction, e.g., the dielectric constant (Dk) and the loss tangent (Df) extraction. The theoretical formulas of the resonance frequency and Q-factor of the resonator are presented. In real measurement, the TM010 mode cylindrical cavity resonator needs to be excited by the probe. The study emphasizes the impact of probe orientation, location, and field distribution on the accuracy of material property extraction. The relationship between cavity dimensions and resonance frequency is explored, highlighting the influence of cavity …
High-Speed Channel Simulator Using Neural Language Models,
2024
Missouri University of Science and Technology
High-Speed Channel Simulator Using Neural Language Models, Hyunwook Park, Yifan Ding, Ling Zhang, Natalia Bondarenko, Hanqin Ye, Brice Achkir, Chulsoon Hwang
Electrical and Computer Engineering Faculty Research & Creative Works
In this paper, high-speed channel simulators using neural language models are proposed. Given the input sequence of geometry design parameters of differential channels, the proposed channel simulator predicts SI characteristic sequences such as insertion loss (IL) and far-end crosstalk (FEXT). Sequence-to-sequence (seq2seq) networks using a recurrent neural network (RNN) and a long short-term memory (LSTM) are utilized for the estimator. Moreover, a transformer network which is a recent neural engine of large language models (LLMs) is introduced for the first time. Compared to seq2seq networks, the transformer network-based simulator can achieve shorter computing time due to its parallel computation called …
Design Of Waveguide Probe For Emi Characterization Of Ddr5 Sodimm,
2024
Missouri University of Science and Technology
Design Of Waveguide Probe For Emi Characterization Of Ddr5 Sodimm, Xiangrui Su, Junho Joo, Minsu Lee, Jeongho Ju, Hyunsik Kim, Taeil Bae, Haekang Jung, Chulsoon Hwang
Electrical and Computer Engineering Faculty Research & Creative Works
In the latest portable electronic devices, 5th generation double data rate small outline dual in-line memory modules (DDR5 SODIMMs) are more and more used and have been identified as one of the critical electromagnetic interferences (EMI) noise sources that could cause RF desensitization. In this paper, the radiation mechanism of DDR5 SODIMM deployed in a laptop is identified and investigated based on near-field scanning. It was found that a cavity formed by the SODIMM and the main board can generate strong radiation around 2.4 GHz due to their dimensions, which overlap with the Wi-Fi band. To quantify the radiation from …
Behavior Model Of A Multiphase Voltage Regulator Module With Rapid Voltage Drop Protection,
2024
Missouri University of Science and Technology
Behavior Model Of A Multiphase Voltage Regulator Module With Rapid Voltage Drop Protection, Junho Joo, Hanyu Zhang, Hanfeng Wang, Wei Shen, Zhigang Liang, Lihui Cao, Seungtaek Jeong, Chulsoon Hwang
Electrical and Computer Engineering Faculty Research & Creative Works
In this paper, a modeling method of voltage regulator module (VRM) with rapid voltage drop protection is introduced. The proposed VRM model captures a pulse-width modulation scheme developed to counteract substantial load currents with high di/dt, resulting in a large voltage drop across the power delivery network (PDN). The equations to describe the non-linear behavior associated with the multiphase VRM behavior are proposed and successfully validated for both light and heavy loads, the latter being particularly crucial to trigger the voltage drop protection measures.
Analytical Modeling Of Partially-Filled Tm010-Mode Dielectric Resonator For Accurate Dk And Df Extraction,
2024
Missouri University of Science and Technology
Analytical Modeling Of Partially-Filled Tm010-Mode Dielectric Resonator For Accurate Dk And Df Extraction, Mehdi Mousavi, Chaofeng Li, Reza Asadi, Seyedmostafa Mousavi, Reza Vahdani, Xiaoning Ye, Mina Esmaeelpour, Donghyun Kim
Electrical and Computer Engineering Faculty Research & Creative Works
In high-speed printed circuit board (PCB) modeling, the accurate determination of the dielectric constant (DK) and dissipation factor (DF) is crucial for signal integrity analysis at design stage. This paper introduces an analytical approach using a partially filled TM010-mode dielectric resonator, an effective tool for DK and DF extraction of PCB material. We begin by discussing the theoretical underpinnings of TM010-mode dielectric resonators and their applicability in measuring the DK and DF of the material under test. A mathematical model is then presented, linking the resonant characteristics directly to the DK and DF of the dielectric material. The …
Modeling Of Power Distrubition Network (Pdn) Noise Coupling Induced Clock Phase Noise,
2024
Missouri University of Science and Technology
Modeling Of Power Distrubition Network (Pdn) Noise Coupling Induced Clock Phase Noise, Zhekun Peng, Junyong Park, Chaofeng Li, Joey Stecher, Srinivas Venkataraman, Xu Wang, Granthana Rangaswamy, Donghyun Kim
Electrical and Computer Engineering Faculty Research & Creative Works
Phase noise analysis is important to clock design. Noise sources of spurs shown on the phase noise result are challenging to find out due to the unknown source locations and coupling mechanisms. Noise from power distribution network (PDN) is one of the most troublesome sources. A behavioral modeling methodology is proposed to simulate the clock phase noise induced by PDN noise coupling for two different mechanisms: PDN-to-clock additive coupling and PDN-to-PDN up-conversion modulation. The thermal noise and 1/f flicker noise are simplified to provide a straightforward view of spur level. The model can be applied to both single-ended clock and …
Dk And Df Characterization Of Low-Loss Dielectric Liquid By Cylindrical Cavity Resonator,
2024
Missouri University of Science and Technology
Dk And Df Characterization Of Low-Loss Dielectric Liquid By Cylindrical Cavity Resonator, Chaofeng Li, Seyedmehdi Mousavi, Reza Asadi, Seyedmostafa Mousavi, Reza Vahdani, Xiaoning Ye, Kai Wang, Donghyun Kim
Electrical and Computer Engineering Faculty Research & Creative Works
A novel cylindrical cavity resonator-based measurement method was developed to characterize the dielectric property of the low-loss dielectric liquid in the paper. The proposed method can be used to accurately measure the dielectric constant (Dk) and the loss tangent (Df) of the low-loss coolant for signal integrity analysis. The cylindrical cavity resonator works at tangential magnetic (TM010) mode is used in the paper to demonstrate the proposed method. A cylindrical cavity resonator apparatus was designed and investigated using full-wave simulations at first. The relative error of Dk and Df extractions based on the designed apparatus are less than 1% and …
Graph Convolutional Neural Network Assisted Genetic Algorithm For Pdn Decap Optimization,
2024
Missouri University of Science and Technology
Graph Convolutional Neural Network Assisted Genetic Algorithm For Pdn Decap Optimization, Haran Manoharan, Jack Juang, Ling Zhang, Hanfeng Wang, Jingnan Pan, Kelvin Qiu, Xu Gao, Chulsoon Hwang
Electrical and Computer Engineering Faculty Research & Creative Works
This paper proposes a hybrid algorithm combining reinforcement learning (RL) and a genetic algorithm (GA) for PDN decap optimization. The trained RL agent uses a graph convolutional neural network as a policy network and predicts the decap solution for a given PDN impedance and target impedance, which is seeded as an initial population to the GA. The trained RL agent is scalable regarding the number of decap ports. The main goal is to save computation time and find the near global minimum or global minimum. Generalization of the algorithm to different decap libraries is achieved through transfer learning, eventually reducing …
Cascading Of 2d And 3d Simulations Of Asic Substrate Interconnect Up To 100 Ghz,
2024
Missouri University of Science and Technology
Cascading Of 2d And 3d Simulations Of Asic Substrate Interconnect Up To 100 Ghz, Zhekun Peng, Junyong Park, Sathvika Bandi, Santosh Pappu, Srinivas Venkataraman, Xu Wang, Granthana Ranzaswamy, Donghyun Kim
Electrical and Computer Engineering Faculty Research & Creative Works
A method of cascading 3D models and 2D models to model the full channel of ASIC package substrate interconnects is proposed, showing good match to full-wave results in S-parameter and TDR up to 100 GHz.
Impact Of Non-Functional Pads Location On Eye Diagram Performance,
2024
Missouri University of Science and Technology
Impact Of Non-Functional Pads Location On Eye Diagram Performance, Mehdi Mousavi, Kevin Cai, Junyong Park, Chaofeng Li, Manish K. Mathew, Reza Asadi, Shameem Ahmed, Donghyun Kim, Bidyut Sen
Electrical and Computer Engineering Faculty Research & Creative Works
This study shows that placing four NFPs in selective PCB layers significantly improves signal integrity, reducing minimum jitter from 18.28 ps to 12.81 ps and maximum jitter from 27.66 ps to 22.03 ps.
Suppression Of Power Distribution Network Pcb-Package Resonance For Low Target Impedance,
2024
Missouri University of Science and Technology
Suppression Of Power Distribution Network Pcb-Package Resonance For Low Target Impedance, Francesco De Paulis, Faye Squires, Yifan Ding, Matteo Cocchini, Matthew Doyle, Samuel Connor, Albert E. Ruehli, Chulsoon Hwang, Lijun Jiang
Electrical and Computer Engineering Faculty Research & Creative Works
The suppression of the large resonance peak that may appear due to the equivalent parallel circuit between the package capacitance and PCB inductance is discussed. Such resonance may be amplified if the decoupling capacitors are not appropriately selected. The relevant parameters involved in the PDN design, and a feasible solution strategy are presented based on the identification of a simplified equivalent circuit that is able to replicate the resonant behavior. The optimization of the relevant parameters of such circuit are able to suggest the best strategy for identifying the decoupling capacitors with appropriate values of parasitic inductance and resistance.
Impact Of Aging On Pim And Dc Resistance Of Fabric-Over-Foam Metallic Contacts,
2024
Missouri University of Science and Technology
Impact Of Aging On Pim And Dc Resistance Of Fabric-Over-Foam Metallic Contacts, Kalkidan W. Anjajo, Seunghun Ryu, Shengxuan Xia, Gracie Boyer, Yuchu He, Haicheng Zhou, Hanfeng Wang, Jonghyun Park, Chulsoon Hwang
Mechanical and Aerospace Engineering Faculty Research & Creative Works
In this paper the impact of aging on the level of passive intermodulation (PIM) and DC resistance of fabric-over-foam metallic contacts is presented. These contacts are widely used to maintain metallic connections between modules and chassis in electronic devices. The PIM caused by the loose metallic contact of these materials mainly affects a receiver's RF sensitivity in mobile devices. This aging test under elevated temperature and relative humidity conditions offers an experiment-based approach with respect to various metallic contact cases. Energy dispersive spectroscopy and scanning electron microscopy are used to characterize the change in material composition and the contact surface …
Experimental Study Of Pcb Vibration Induced By Mlcc Assembly Orientation And Process Variations,
2024
Missouri University of Science and Technology
Experimental Study Of Pcb Vibration Induced By Mlcc Assembly Orientation And Process Variations, Yifan Ding, Ming Feng Xue, Jianmin Zhang, Xin Hua, Benjamin Leung, Eric A. Macintosh, Chulsoon Hwang
Electrical and Computer Engineering Faculty Research & Creative Works
The piezoelectric effect will cause the multilayer ceramic capacitor (MLCC) to deform in several directions. When it is soldered to the printed circuit board (PCB) and powered on, these deformations will exert a certain force on the PCB, causing the PCB to vibrate and emit acoustic noise at a certain frequency. Determining the dominant deformation direction that MLCC can affect the PCB is relevant and important for efficiently extracting the equivalent source of noise. This paper provides a method to determine the dominant deformation direction produced by MLCC, explores it through experimental measurement results, and finally provides a conclusion to …
