The purpose of this study is to develop accuracy enhancement techniques for the Time Domain Reflection/Transmission (TDR/T) measurements including the analysis of the error sources for the Enhanced Accuracy TDR/T (EA-TDR/T). These TDR/T techniques are used for IC and IC package interconnect characterization and equivalent circuit model extraction, which are important for evaluating the overall system performance in today's digital IC design. The frequency domain error correction has been used to get parameters for a Device Under Test (DUT) from time domain measurements. The same technique can be used as an intermediate step for obtaining the EA-TDR/T. Careful choice of the acquisition window and precise alignment of the DUT and calibration standard waveforms are necessary to get the accuracy enhancement for the TDR/T. Improved FFT techniques are used in order to recover the actual spectra of the step-like time domain waveforms acquired with an acquisition window with a finite time length. The EA-TDR/T waveform are recovered from error corrected frequency domain parameters of the DUT by launching an ideal excitation at the DUT and finding the response. The rise time of the ideal excitation can be faster than that of the physical excitation in the measurement system. However, excessive high-frequency noise can enter the system if the rise time of the ideal excitation is chosen to be too high. The resulting EA-TDR/T waveforms show significantly less aberrations than the conventional TDR/T waveforms, hence allow us to extract accurate equivalent circuit model for the DUT, which in our case is IC interconnects. / Graduation date: 1995

The improved accuracy of Time Domain Reflection and Transmission (TDR/T) measurements made possible by the calibration process known as Time Domain Network Analysis (TDNA) is applied to the problem of characterization and modeling of electronic interconnect and packaging structures. TDNA uses measurements of known and partially known calibration standards to characterize the measurement system allowing for the correction of the raw measurements of an unknown network to eliminate the effects of system non-idealities and resulting in a significant improvement of the measurement quality. The correction process is shown to be analogous to the well established Frequency Domain Vector Network Analyzer calibrations and to have the same capabilities for high precision metrology applications. Methods are developed to extract electrical circuit models from time domain measurements of lossless, nonuniform, multiconductor transmission lines for two broad classes of structures. Although unique solutions are not feasible for general structures that scatter the propagating wave-front, approximate solutions have been identified using the assumption of a single velocity wave-front, the case for homogeneous media. For structures with identical lines, such as a parallel line bus structure, the propagation behavior (eigenvector matrix) is determined only by the number of conductors, N, and is therefore known a priori for the entire structure allowing decoupling of the system into N orthogonal nonuniform transmission lines. Circuit models have been developed for these decoupled nonuniform lines as well as for the equal modal velocity assumption which relies on a matrix impedance profile to fully describe the system. The implications of non-ideal grounding of interconnection circuits is explored. Traditional lumped element methods for modeling these effects are examined and typical examples where distributed circuit models are necessary to adequately describe the system are identified. Techniques for examining power-planes and substrate connections in integrated circuits and integrated circuit packages using the distributed ground model are presented. Novel circuit design methods to circumvent the limitations imposed by non-ideal grounds and nonzero length transmission structures are also proposed. / Graduation date: 1994

Thesis (Ph. D.)--University of Texas at Dallas, 2006. / Includes vita. Includes bibliographical references (leaves 253-256).

Until now, few rigorous studies of the precursors in structures exhibiting superluminal group velocities have been performed. One dimensional photonic crystals(1DPC) and active Lorentzian media are among the ones which are able to exhibit superluminal propagation. In the first part of the thesis we have studied the evolution of the precursors in active Lorentzian media and 1DPC. The problem of the propagation of the precursors in active Lorentzian media is addressed, by employing the steepest descent method to provide a detailed description of the propagation of the pulse inside the dispersive medium in the time domain. The problem of the time and frequency evolution of the precursors in 1DPC is studied, using the finite-difference time-domain (FDTD) techniques in conjunction with joint time-frequency analysis (JTFA). Our study clearly shows that the precursor fields associated with superluminal pulse propagation travel at subluminal speeds. It is also shown that FDTD analysis and JTFA can be combined to study the dynamic evolution of the transient and steady state pulse propagation in dispersive media. The second part of the thesis concentrates on the applications of the precursors. An interesting property of the precursors is their lower than exponential attenuation rate inside a lossy dielectric, such as water. This property of the precursors has made them an interesting candidate for applications such as ground penetrating radar and underwater communication. It was recently pointed out that a pulse which is generated inside of water and assumes the shape of the Brillouin precursor would be optimally suited for long range propagation in water (described by the single-pole Debye model). Here, we have considered the optimal pulse propagation problem, accounting for the interaction of the pulse with the air/water interface at oblique incidence. In addition, we argue that pulse excitations which are rough approximation of the Brillouin precursor will eventually evolve into the Brillouin precursor itself shortly after they enter water. Therefore, the excitation of a long-propagating pulse is not sensitive to its shape. Finally, we studied the performance of the optimized pulse in terms of the energy of the scattered field from an object inside water. Based on the simulation results the optimized pulse scattered field has higher energy compared to pulses with the same energy and different temporal distribution. The FDTD technique is employed in all the simulations.

Until now, few rigorous studies of the precursors in structures exhibiting superluminal group velocities have been performed. One dimensional photonic crystals(1DPC) and active Lorentzian media are among the ones which are able to exhibit superluminal propagation. In the first part of the thesis we have studied the evolution of the precursors in active Lorentzian media and 1DPC. The problem of the propagation of the precursors in active Lorentzian media is addressed, by employing the steepest descent method to provide a detailed description of the propagation of the pulse inside the dispersive medium in the time domain. The problem of the time and frequency evolution of the precursors in 1DPC is studied, using the finite-difference time-domain (FDTD) techniques in conjunction with joint time-frequency analysis (JTFA). Our study clearly shows that the precursor fields associated with superluminal pulse propagation travel at subluminal speeds. It is also shown that FDTD analysis and JTFA can be combined to study the dynamic evolution of the transient and steady state pulse propagation in dispersive media. The second part of the thesis concentrates on the applications of the precursors. An interesting property of the precursors is their lower than exponential attenuation rate inside a lossy dielectric, such as water. This property of the precursors has made them an interesting candidate for applications such as ground penetrating radar and underwater communication. It was recently pointed out that a pulse which is generated inside of water and assumes the shape of the Brillouin precursor would be optimally suited for long range propagation in water (described by the single-pole Debye model). Here, we have considered the optimal pulse propagation problem, accounting for the interaction of the pulse with the air/water interface at oblique incidence. In addition, we argue that pulse excitations which are rough approximation of the Brillouin precursor will eventually evolve into the Brillouin precursor itself shortly after they enter water. Therefore, the excitation of a long-propagating pulse is not sensitive to its shape. Finally, we studied the performance of the optimized pulse in terms of the energy of the scattered field from an object inside water. Based on the simulation results the optimized pulse scattered field has higher energy compared to pulses with the same energy and different temporal distribution. The FDTD technique is employed in all the simulations.

It is well known that the finite difference time domain (FDTD) method is a powerful numerical analysis tool for solving electromagnetic problems. In a simulated area, in order to discretize an object which is much smaller than the others, a very small space increment is needed and hence the time step should be decreased too for stability consideration in traditional FDTD. The small space and time increments will respectively increase the memory requirement and calculation time. To overcome these problems, some numerical methods were developed, such as the subcell and nonuniform grid method, to handle the small feature size. This thesis describes an efficient method for generating FDTD subcell equations. We construct a second order macromodel system instead of the subcell region in conventional FDTD. The macromodel system can be reduced with model order reduction techniques (MOR) and then translated into new FDTD update equations. When the problem contains several objects of the same size and material properties, the MOR subcell has the advantage of reusability. This means that the reduce-order model of the object needs to be generated only once nonetheless can be applied to every position where the objects originally occupied.

¡@In this thesis, a novel subgridding scheme is proposed based on the hybridization of the FDTD and CNDG-FDTD algorithms. The FDTD method is applied to the coarse grid region, while the CNDG-FDTD method is used in the fine grid region. Because of the unconditional stability of the CNDG scheme, the temporal step size can be set equal to that in the coarse grid region to speed up the computation in the fine grid region. Furthermore, the temporal interpolation at the fine and coarse grids interface is no longer necessary and thus the complexity of spatial interpolation is largely reduced. ¡@As the CNDG-FDTD method is free from the CFL condition restraint, it saves a large amount of CPU time. Numerical results agree very well with that of the FDTD scheme. But it requires a larger amount of computer memory, at least 20% more than the FDTD method. A modified version of the CNDG-FDTD scheme with increased memory efficiency is also presented. It has not only eliminated the restraint of the CFL condition, but also achieved a more efficient saving of CPU time and computer memory requirements.

No description available.

When we use the FDTD method to analyze electromagnetic problems, it has to properly discretize the space and time. Automeshing can non-uniformly discretize the simulated structure and generate gradual grids. To improve the efficiency of automeshing, we optimize the parameter of automeshing using the genetic algorithm. Without sacrificing accuracy, it searches a suitable ratio to reduce the generated grids and to save simulation time. At last, we optimize the PIFA using genetic algorithm and search automatically the height of the substrate and the feed position in order to obtain optimal performance. When we use the genetic algorithm, it is the key point to define an objective function evaluating the fitness of the optimized problem. It is important that the function has to appropriately describe the performance at that time.

In this work, based on both experimental and theoretical approach, the contact ESD behavior on a PCB circuit is investigated. The discharge mechanisms of ESD (Electrostatic Discharge) phenomena are discussed by both practical measurement and mathematic analysis. Simplified mathematic models include CR-R¡BCR-C and CR-L are proposed to explain the low frequency phenomena of ESD discharge events. Moreover, some experimental setups with good repeatability are demonstrated for measuring the ESD-induced noise on high-speed PCB and some countermeasures are suggested to reduce ESD damage.