Broadband whole package FDTD simulation

Whole package analysis is becoming more and more important with the rapid expansion of high frequency electronics. The motivation of this thesis is to find and implement a new method for broadband whole package simulation. 3-dimension (3-D) whole package Finite Difference Time Domain (FDTD) simulation result was first reported in detail in this thesis. The FDTD method is a widely used full-wave time-domain simulation method used in the design and analysis for electromagnetic (EM) systems, such as antennas, wave propagating, and microwave circuits. Absorbing boundary condition (ABC), such as the perfect matched layer (PML) method, makes it possible to accurately analyze an EM structure involving complicated wave propagation in three-dimensional domain. Instead of running simulation at each frequency, time-domain solution gives complete frequencydomain response including coupling and dispersion effects. Chapter2 introduces the principle of FDTD and two important boundary condition methods. It also discusses the nonuniform grid numerical error, and gives the FDTD simulation and theoretical result. Flip chip package is one of the most important package types. Chapter 3 presents a wide band approach for characterizing multiple flip chips interconnects by the FDTD method. Detailed analysis for electrical performance for frequencies up to 40 GHz has been performed with variations of interconnect bumps (ball cross section and via cross section). Flip chips of three sizes are studied using FDTD method in detail. The relationship between reflection loss, via pad length, ball crosssection and via cross section is tabulated for future packaging design. Based on the simulation results, some design approaches are proposed for packaging structure operating at near 40 GHz. FDTD whole package simulation method is introduced at the beginning of Chapter 4, followed by discussion how to implement this method to specific packages. The packages used to host circuit in chapter 4 are microstrip line and fiip chip interconnects. The embedded circuits are ideal transmission line and an HP amplifier. Transient effects are observed when an amplifier is hosted in a package. Most of the simulations are processed under three-dimensional environment; twodimensional simulation is used for reference standard. All these results were first reported by the author of this thesis and his collaborators

FDTD-based full wave co-simulation model for hybrid electromagnetic systems

In high-frequency ranges, the present electronic design automation software has limited capabilities to model electromagnetic (EM) systems where there are strong field effects influencing their characteristics. In this situation, a full-wave simulation tool is desired for the analysis and design of high-speed and non-linear EM systems. It is necessary to explore the interaction between the field and electronic components during a transient process when field effects are more significant. The finite-difference time-domain (FDTD) technique receives growing attention in the area of EM system analysis and simulation due to its simplicity, flexibility and robustness. It is a full-wave simulation method that solves the Maxwell\u27s equations in time domain directly. Decades of research and development and rapid growth in computer capability have built up a firm foundation for FDTD techniques to be applied to many practical problems. Based on FDTD, this dissertation develops a stable CO-simulation method to perform a full-wave simulation of a hybrid EM system consisting of lumped elements and distributed structures. In this method, FDTD is used to solve the EM field problems associated with distributed structures, and a circuit simulator solves the response of lumped elements. A field-circuit model proposed in the dissertation serves as the interface between the two simulation tools. Compared with previous methods, the FDTD method based on this model is much more flexible and stable for linear and nonlinear lumped elements under both small and large signal conditions. Because of its flexibility and robustness, this model is a promising approach to integrate a field solver and a circuit simulator in the simulations of practical EM systems. In order to improve the simulation accuracy, some problems related to FDTD simulation are studied. Based on the numerical dispersion in homogeneous media uniform grids, the FDTD numerical reflection and transmission on the boundary of media, which are discritized by a non-uniform grid, are investigated. This investigation provides for the first time an estimation of FDTD numerical error in inhomogeneous media and non-uniform grids. Perfectly matched layer (PML) was previously utilized the homogeneous media or uniform grids. This dissertation extends the PML boundary conditions to handle the inhomogeneous media and non-uniform grid. Techniques extracting S parameters from FDTD simulation are also discussed. Two and three-dimensional CO-simulation software, written in C++, has be derived, developed and verified in this dissertation. The simulation results agree well with results from other simulation methods, like SPICE, for many test circuits. Taking data sampling and interpolation into account, simulation results generally fit well to measurement and other simulation results for complicated three-dimensional structures. With further improvements of the FDTD technique and circuit simulation, field-circuit CO-simulation model will widen its application to general EM systems

Some recent advances in numerical solutions of electromagnetic problems.

Zhang Kai.Thesis (M.Phil.)--Chinese University of Hong Kong, 2005.Includes bibliographical references (leaves 99-102).Abstracts in English and Chinese.Chapter 1 --- Introduction --- p.6Chapter 1.1 --- The Generalized PML Theory --- p.6Chapter 1.1.1 --- Background --- p.6Chapter 1.1.2 --- Derivation --- p.8Chapter 1.1.3 --- Reflection Properties --- p.11Chapter 1.2 --- Unified Formulation --- p.12Chapter 1.2.1 --- "Face-, Edge- and Corner-PMLs" --- p.12Chapter 1.2.2 --- Unified PML Equations in 3D --- p.15Chapter 1.2.3 --- Unified PML Equations in 2D --- p.16Chapter 1.2.4 --- Examples of PML Formulations --- p.16Chapter 1.3 --- Inhomogeneous Initial Conditions --- p.23Chapter 2 --- Numerical Analysis of PMLs --- p.25Chapter 2.1 --- Continuous PMLs --- p.26Chapter 2.1.1 --- PMLs for Wave Equations --- p.27Chapter 2.1.2 --- Finite PMLs for Wave Equations --- p.31Chapter 2.1.3 --- Berenger's PMLs for Maxwell Equations --- p.33Chapter 2.1.4 --- Finite Berenger's PMLs for Maxwell Equations --- p.35Chapter 2.1.5 --- PMLs for Acoustic Equations --- p.38Chapter 2.1.6 --- Berenger's PMLs for Acoustic Equations --- p.39Chapter 2.1.7 --- PMLs for 1-D Hyperbolic Systems --- p.42Chapter 2.2 --- Discrete PMLs --- p.44Chapter 2.2.1 --- Discrete PMLs for Wave Equations --- p.44Chapter 2.2.2 --- Finite Discrete PMLs for Wave Equations --- p.51Chapter 2.2.3 --- Discrete Berenger's PMLs for Wave Equations --- p.53Chapter 2.2.4 --- Finite Discrete Berenger's PMLs for Wave Equations --- p.56Chapter 2.2.5 --- Discrete PMLs for 1-D Hyperbolic Systems --- p.58Chapter 2.3 --- Modified Yee schemes for PMLs --- p.59Chapter 2.3.1 --- Stability of the Yee Scheme for Wave Equation --- p.61Chapter 2.3.2 --- Decay of the Yee Scheme Solution to the Berenger's PMLs --- p.62Chapter 2.3.3 --- Stability and Convergence of the Yee Scheme for the Berenger's PMLs --- p.67Chapter 2.3.4 --- Decay of the Yee Scheme Solution to the Hagstrom's PMLs --- p.70Chapter 2.3.5 --- Stability and Convergence of the Yee Scheme for the Hagstrom's PMLs --- p.75Chapter 2.4 --- Modified Lax-Wendroff Scheme for PMLs --- p.80Chapter 2.4.1 --- Exponential Decays in Parabolic Equations --- p.80Chapter 2.4.2 --- Exponential Decays in Hyperbolic Equations --- p.82Chapter 2.4.3 --- Exponential Decays of Modified Lax-Wendroff Solutions --- p.86Chapter 3 --- Numerical Simulation --- p.93Bibliography --- p.9

Computation of Electromagnetic Fields in Assemblages of Biological Cells Using a Modified Finite-Difference Time-Domain Scheme

When modeling objects that are small compared with the wavelength, e.g., biological cells at radio frequencies, the standard finite-difference time-domain (FDTD) method requires extremely small time-step sizes, which may lead to excessive computation times. The problem can be overcome by implementing a quasi-static approximate version of FDTD based on transferring the working frequency to a higher frequency and scaling back to the frequency of interest after the field has been computed. An approach to modeling and analysis of biological cells, incorporating a generic lumped-element membrane model, is presented here. Since the external medium of the biological cell is lossy material, a modified Berenger absorbing boundary condition is used to truncate the computation grid. Linear assemblages of cells are investigated and then Floquet periodic boundary conditions are imposed to imitate the effect of periodic replication of the assemblages. Thus, the analysis of a large structure of cells is made more computationally efficient than the modeling of the entire structure. The total fields of the simulated structures are shown to give reasonable and stable results at 900,1800, and 2450 MHz. This method will facilitate deeper investigation of the phenomena in the interaction between electromagnetic fields and biological systems

Numerical techniques for electromagnetic applications in microelectronic and radar imaging systems

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1998.Includes bibliographical references (p. 227-242).by Jerome J. Akerson.Ph.D

Production of herbal shampoo from Madagascar periwinkle

Recently, the society interest in using herbal shampoos has increased significantly. Big companies have started to produce herbal shampoo to meet the market demands. However, most of these shampoos contain chemicals that could be harmful to human health. The main purpose of this study are to produce homemade herbal shampoo from Madagascar Periwinkle plant without harmful chemicals and have additional benefits to consumers. By using stem and leaf extract from the plant and cold press machine, we analysed the quantitative aspect of the extracts and use it as a main ingredient to produce homemade herbal shampoo. The extracts are then used as ingredients in production of the shampoo. Several tests were conducted to determine the performance of the shampoos. The Fourier Transform Infrared Spectroscopy (FTIR) analysis shows presence oh -OH groups and C=O bond to indicate the presence of vinca alkaloids. The performance tests result inconsistent to one extract only. This study provided an information to future researchers regarding the study of Madagascar Periwinkle and effectiveness of this plant in herbal shampoos production

An Investigation of the Accuracy of Finite-Volume Radial Domain Truncation Technique

© Copyright 2007 IEEE. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the IEEE. This material is presented to ensure timely dissemination of scholarly and technical work. Copyright and all rights therein are retained by authors or by other copyright holders. All persons copying this information are expected to adhere to the terms and constraints invoked by each author's copyright. In most cases, these works may not be reposted without the explicit permission of the copyright holder.The accuracy and performance of the radial domain truncation technique is presented in the framework of finite-volume time-domain method. In the present approach all the electromagnetic field quantities are co-located in both space and time and the performance is evaluated using unstructured grid. The influence of the radius of curvature of the absorber is investigated using a waveguide and a horn-antenna as practical examples. Numerical reflection errors are computed using a reference solutions and the convergence of the results is studied for increasing radius of curvature of the absorber. Low-level effects on the antenna radiation patterns further illustrates the convergence of the technique.Krishnaswamy Sankaran, Christophe Fumeaux and Rudiger Vahldiec

Computation of Electromagnetic Fields in Assemblages of Biological Cells Using a Modified Finite-Difference Time-Domain Scheme

When modeling objects that are small compared with the wavelength, e.g., biological cells at radio frequencies, the standard finite-difference time-domain (FDTD) method requires extremely small time-step sizes, which may lead to excessive computation times. The problem can be overcome by implementing a quasi-static approximate version of FDTD based on transferring the working frequency to a higher frequency and scaling back to the frequency of interest after the field has been computed. An approach to modeling and analysis of biological cells, incorporating a generic lumped-element membrane model, is presented here. Since the external medium of the biological cell is lossy material, a modified Berenger absorbing boundary condition is used to truncate the computation grid. Linear assemblages of cells are investigated and then Floquet periodic boundary conditions are imposed to imitate the effect of periodic replication of the assemblages. Thus, the analysis of a large structure of cells is made more computation-ally efficient than the modeling of the entire structure. The total fields of the simulated structures are shown to give reasonable and stable results at 900, 1800, and 2450 MHz. This method will facilitate deeper investigation of the phenomena in the interaction between electromagnetic fields and biological systems. Index Terms-Finite difference time domain (FDTD), Floquet periodic boundary conditions, quasi-static method

Electromagnetic Wave Theory and Applications

Contains table of contents for Section 3, reports on ten research projects and a list of publications.National Aeronautics and Space Administration Contract 958461U.S. Navy - Office of Naval Research Grant N00014-92-J-1616U.S. Navy - Office of Naval Research Grant N00014-89-J-1019U.S. Navy - Office of Naval Research Grant N00014-90-J-1002U.S. Army Cold Regions Research and Engineering Laboratory Contract PACA89-95-K-0014Mitsubishi Corporation Agreement Dated 8/31/95U.S. Navy - Office of Naval Research Grant N00014-92-J-4098U.S. Federal Aviation Administration Grant 94-G-007DEMACO Corporation Contract DEM-95-MIT-55Joint Services Electronics Program Contract DAAH04-95-1-003

FDTD Analysis of Plasmonic and Nanojet Enhanced Photodetectors for Improved Performance

The finite-difference time-domain (FDTD) technique is a very flexible and robust means to solve problems spanning a broad range of applications (defense, communication, computing, semiconductor devices and biomedicine), especially where geometrical complexities, nonlinearities and multiphysics dominate. In this thesis, novel photodetectors are developed via FDTD having sub-wavelength active areas that yield enhanced optical absorption at near-infrared (NIR) wavelengths by way of plasmonics or photonic nanojets. The response time of photodiodes is primarily limited by two factors: (1) the transit time of photo-generated carriers to the electrode and (2) depletion layer capacitance of the semiconductor. The former requires a thinner depletion layer, resulting in a large depletion layer capacitance. To suppress the increase of the depletion layer capacitance, it is necessary to decrease the active area of the photodiode with depletion layer thickness. However, the smaller the active area the lower the output of the photodiode under the constant optical power density. To overcome the trade-off between speed and responsivity, the incident light should be efficiently confined within a small active area. Surface plasmons play an important role in this phenomenon as surface plasmons can enhance the near-field when excited by a certain wavelength. Resonant surface plasmons can confine strong optical near fields in a sub wavelength volume, this has been demonstrated for near- infrared dipole antennas. As an alternative to plasmonics it is proposed here that photonic nanojets may be employed to focus light onto the small active region of a photodetector. A photonic nanojet is a narrow, high-intensity electromagnetic beam that propagates into the background medium from the shadow side surface of a plane-wave illuminated loss-less dielectric micro-cylinder or micro-sphere of diameter greater than the illuminating wavelength, λ. The transverse beam width of the nanojet can be as small as λ/3 and length can be as long as 20λ, so we can use a photonic nanojet to concentrate the energy into a small region. By using the E-field enhancement in a sub-wavelength active area provided by the photonic nanojet and comparing it with the enhancement of the plasmonic structures, we may improve the responsivity and speed of the photodetector