Modal based BGA modeling in high-speed package

In the Section 1, the improved Root-Omega method for extracting dielectric properties from fabricated multilayer printed circuit boards is proposed. Based on the electrical properties of fabricated transmission lines, the improved Root-Omega method applied to cases with smooth and rough conductors is validated using simulations. Error sensitivity analysis is performed to demonstrate the potential errors in the original Root-Omega procedure and the error sensitivity is significantly reduced by the proposed improvements. In the Section 2, a fast modal-based approach is developed to accurately and efficiently capture the proximity effect. Image theory is also applied in the proposed approach to reduce the computational domain from 3D structure to 2D. The matrix reduction approach is applied to obtain the physical loop inductance. The lumped capacitance is obtained. A π topology equivalent circuit model for the BGA structure is built. Good agreement between the equivalent circuit model and full wave simulation can be achieved up to 40GHz. In the Section 3, the proximity effect for BGAs between parallel plates is carefully considered. A modal-based cavity method is proposed to extract the partial inductance of two parallel plates. The modal basis function is used to count for the non-uniformly distributed current density. The physical loop inductance is further obtained from the matrix reduction approach. The extracted physical loop inductance is validated with a commercial finite element method-based tool. The boundary effect is demonstrated in the inductance extraction. The proposed method is used to optimize for the power distributed network design --Abstract, page iii

Improved attenuation and crosstalk modeling techniques for high-speed channels

”As digital systems are moving in the direction of faster data transmission rate and higher density of circuits, the problem of the far-end crosstalk (FEXT) and frequency-dependent attenuation are becoming the major factors that limit signal integrity performance. This research is focusing on providing several more comprehensive and accurate modeling approaches for striplines on fabricated printed circuit board (PCB). By characterizing the dielectric permittivity of prepreg and core, dielectric loss tangent, and copper foil surface roughness using measurement data, a better agreement between the stripline model and measurement is achieved. First, a method is proposed to extract dielectric loss tangent using coupled striplines’ measured S-parameters and cross-section geometry. By relating modal attenuation factors to the ratio between the differential and common mode per-unit-length resistances, the unknwon surface roughness contribution is eliminated and the contributions of dielectric and conductor loss are separated. In addition, an improved surface roughness modeling approach is proposed by analyzing the microscopical cross-sectional image of the stripline. By combining the characterized surface roughness information and the extracted dielectric properties, the modeled attenuation factor is match with the measurement data. At last, an approach is introduced to extract the dielectric permittivity of prepreg and core. Using known cross-sectional geometry and measured phase of the coupled stirplines under test, the capacitance components in prepreg and core are separated using 2D solver models. Using the stripline model with inhomogeneous dielectric material, more accurate FEXT modeling results are obtained”--Abstract, page iv

Design and Control of Power Converters for High Power-Quality Interface with Utility and Aviation Grids

Power electronics as a subject integrating power devices, electric and electronic circuits, control, and thermal and mechanic design, requires not only knowledge and engineering insight for each subarea, but also understanding of interface issues when incorporating these different areas into high performance converter design.Addressing these fundamental questions, the dissertation studies design and control issues in three types of power converters applied in low-frequency high-power transmission, medium-frequency converter emulated grid, and high-frequency high-density aviation grid, respectively, with the focus on discovering, understanding, and mitigating interface issues to improve power quality and converter performance, and to reduce the noise emission.For hybrid ac/dc power transmission,• Analyze the interface transformer saturation issue between ac and dc power flow under line unbalances.• Proposed both passive transformer design and active hybrid-line-impedance-conditioner to suppress this issue.For transmission line emulator,• Propose general transmission line emulation schemes with extension capability.• Analyze and actively suppress the effects of sensing/sampling bias and PWM ripple on emulation considering interfaced grid impedance.• Analyze the stability issue caused by interaction of the emulator and its interfaced impedance. A criterion that determines the stability and impedance boundary of the emulator is proposed.For aircraft battery charger,• Investigate architectures for dual-input and dual-output battery charger, and a three-level integrated topology using GaN devices is proposed to achieve high density.• Identify and analyze the mechanisms and impacts of high switching frequency, di/dt, dv/dt on sensing and power quality control; mitigate solutions are proposed.• Model and compensate the distortion due to charging transition of device junction capacitances in three-level converters.• Find the previously overlooked device junction capacitance of the nonactive devices in three-level converters, and analyze the impacts on switching loss, device stress, and current distortion. A loss calculation method is proposed using the data from the conventional double pulse tester.• Establish fundamental knowledge on performance degradation of EMI filters. The impacts and mechanisms of both inductive and capacitive coupling on different filter structures are understood. Characterization methodology including measuring, modeling, and prediction of filter insertion loss is proposed. Mitigation solutions are proposed to reduce inter-component coupling and self-parasitics

Characterizing and modeling methods for power converters

“Stable power delivery is becoming increasingly important in modern electronic devices, especially in applications with stringent requirements of its form factor. With the evolution of technology, the switching frequency in a power converter is pushed to a higher frequency range, e.g., several MHz or even higher, to decrease its size. However, the loss generated in the converter increases drastically due to the high switching frequency. In addition, a wide-band feedback controller is required to accommodate the high switching frequency in the converter. We focus on the characterization or modeling of the feedback control circuits and critical components in a switching power converter. A transient-simulation-oriented averaged continuous-time model is proposed to evaluate the transient output noise of a buck converter. The proposed modeling method is developed with time-domain waveforms, which enables a generalized modeling framework for current-mode controllers with constant and nonconstant switching frequencies. In this work, we mainly focus on characterization for two types of components: the switching components, including Si MOSFETs and GaN High-electron-mobility transistor (HEMT), and the magnetic core in an inductor. For the characterization of switching components, a set of test fixtures are designed to characterize the equivalent circuit of Si MOSFETs and GaN HEMTs. The frequency-dependent behaviors of Si MOSFETs are observed, which invalidate the conventional modeling methods for MOSFETs, especially for radiated emission (RE) prediction. For the characterization of magnetic cores, two different probe calibration methods are demonstrated. Accurate phase discrepancy characterization is allowed with the proposed method, which overcomes the main limitation in the conventional two-winding method. In addition, the proposed method supports wide-band loss measurement without resonance tuning, which supports core loss measurement for non-sinusoidal excitation”--Abstract, page iv

LeakyOhm: Secret Bits Extraction using Impedance Analysis

The threats of physical side-channel attacks and their countermeasures have been widely researched. Most physical side-channel attacks rely on the unavoidable influence of computation or storage on current consumption or voltage drop on a chip. Such data-dependent influence can be exploited by, for instance, power or electromagnetic analysis. In this work, we introduce a novel non-invasive physical side-channel attack, which exploits the data-dependent changes in the impedance of the chip. Our attack relies on the fact that the temporarily stored contents in registers alter the physical characteristics of the circuit, which results in changes in the die's impedance. To sense such impedance variations, we deploy a well-known RF/microwave method called scattering parameter analysis, in which we inject sine wave signals with high frequencies into the system's power distribution network (PDN) and measure the echo of the signals. We demonstrate that according to the content bits and physical location of a register, the reflected signal is modulated differently at various frequency points enabling the simultaneous and independent probing of individual registers. Such side-channel leakage challenges the $t$-probing security model assumption used in masking, which is a prominent side-channel countermeasure. To validate our claims, we mount non-profiled and profiled impedance analysis attacks on hardware implementations of unprotected and high-order masked AES. We show that in the case of the profiled attack, only a single trace is required to recover the secret key. Finally, we discuss how a specific class of hiding countermeasures might be effective against impedance leakage

Persistent monitoring of digital ICs to verify hardware trust

The specialization of the semiconductor industry has resulted in a global Integrated Circuit (IC) supply chain that is susceptible to hardware Trojans - malicious circuitry that is embedded into the chip during the design cycle. This nefarious attack could compromise the missioncritical systems which implement these devices. While a trusted domestic IC supply chain exists with resources such as the Trusted Foundry Program, it\u27s highly desirable to utilize the high yield, fast turn-around time, low cost, and leading-edge technology of the global IC supply chain. Research into the verification of hardware trust has made significant progress in recent years but is still far from a single, comprehensive solution. Most proposed solutions are one-time implementable methods that attempt to detect hardware Trojans during the verification stage of the IC development process. While this is a desirable solution, it\u27s not realistic given the current limitations of hardware Trojan detection techniques. We propose a more comprehensive solution that involves the persistent verification of hardware trust in the field, in addition to several one-time methods implemented during IC verification. We define a persistent verification framework that involves the use of a few ICs from a secure process flow to persistently monitor and verify the operation of several untrusted ICs from the global supply chain. This allows the system integrator to realize the benefits of the global IC supply chain while maintaining the integrity of the system. We develop a system monitor which filters the IO of untrusted digital ICs for a set of patterns, which we refer to as digital signal signatures, to verify the operation of the devices

Advances in Piezoelectric Transducers

The piezoelectric transducer converts electric signals into mechanical vibrations or vice versa by utilizing the morphological change of a crystal which occurs on voltage application, or conversely by monitoring the voltage generated by a pressure applied on a crystal. This book reports on the state of the art research and development findings on this very broad matter through original and innovative research studies exhibiting various investigation directions. The present book is a result of contributions of experts from international scientific community working in different aspects of piezoelectric transducers. The text is addressed not only to researchers, but also to professional engineers, students and other experts in a variety of disciplines, both academic and industrial seeking to gain a better understanding of what has been done in the field recently, and what kind of open problems are in this area

Intermittent fault diagnosis and health monitoring for electronic interconnects

Literature survey and correspondence with industrial sector shows that No-Fault-Found (NFF) is a major concern in through life engineering services, especially for defence, aerospace, and other transport industry. There are various occurrences and root causes that result in NFF events but intermittent interconnections are the most frustrating. This is because it disappears while testing, and missed out by diagnostic equipment. This thesis describes the challenging and most important area of intermittent fault detection and health monitoring that focuses towards NFF situation in electronics interconnections. After introduction, this thesis starts with literature survey and describes financial impact on aerospace and other transport industry. It highlights NFF technologies and discuss different facts and their impact on NFF. Then It goes into experimental study that how repeatedly intermittent fault could be replicated. It describes a novel fault replicator that can generate repeatedly IFs for further experimental study on diagnosis techniques/algorithms. The novel IF replicator provide for single and multipoint intermittent connection. The experimental work focuses on mechanically induced intermittent conditions in connectors. This work illustrates a test regime that can be used to repeatedly reproduce intermittency in electronic connectors whilst subjected to vibration ... [cont.]