Jason D. Morsey

On the Dual Basis for Solving Electromagnetic Surface Integral Equations

A powerful technique for solving electromagnetic (EM) surface integral equations (SIEs) for inhomogenous objects by the method of moments (MoM) involves the well-known Rao-Wilton-Glisson (RWG) basis function to represent the electric current and, for field orthogonality and numerical stability reasons, a variation of the RWG basis known as the ntilde X RWG basis (where ntilde is a unit normal vector at the object surface) to represent the magnetic current. Though this combination provides a numerically efficient and effective solution that has been demonstrated on a variety of structures, one cannot feel entirely comfortable because of the presence of fictitious magnetic current associated with the modified basis. Chen and Wilton proposed a different, smoother basis in 1990 that avoids the fictitious line charges, but because of computational cost issues it has not been used beyond Chens dissertation. Recently, this basis was rediscovered and has received considerable attention. Our work reexamines the dual basis, exploring issues not addressed by Chen and Wilton and showing accurate solutions for a variety of EM scattering structures.

Novel Capacitance Extraction Method Using Direct Boundary Integral Equation Method and Hierarchical Approach

In this paper, a novel hierarchical capacitance extraction method is introduced. It takes advantage of surface integral equations to have far less unknowns than the volumetric method. It uses the divide and conquer strategy to hierarchically solve the dense capacitance matrix efficiently. It partitions the problem into small regions (cells) automatically and each region is analyzed separately. An inverse binary-tree browse procedure is employed to combine cell capacitance matrixes from leafy level of the tree to the root. A global capacitance matrix is obtained at the root without computing charge distribution. Benchmarks using the developed code CSurf are provided to demonstrate its efficiency

The Use of Fast Integral Equations Solvers for Practical Package and Interconnect Analysis

Fast integral equation methods are now being applied to packaging and other such low frequency problems. This paper explores some of the issues surrounding such an application to real, product level packaging and interconnects type structures. Discussed are issues such as low frequency breakdown, mesh aspect ratios, and solver convergence. Finally, integral equation solver examples are presented using the IBM internally developed pre-corrected FFT (PFFT) solver labeled EMSurf

Massively parallel full-wave modeling of advanced packaging structures on BlueGene supercomputer

A parallel, distributed memory version of a full wave method of moments (MoM) solution combined with the reduced coupling approximation technique is presented on the largest parallel-server. Modeling results for product-level simulation of a single-chip module are correlated with time- domain measurements for validation of the technique. Scaling for this and other representative examples are shown for up to 16,384 compute nodes on IBMs BlueGene supercomputer, the largest parallel-platform ever reported for MoM based solutions.

Constructing 3D package component broadband electrical models with correct DC values

Accurate channel simulations of package interconnections require passive and causal models that faithfully represent the full frequency response from tens of gigahertz to DC. In this paper, we propose and test a method to create accurate models extending to DC while retaining passivity and causality. The model derived by this method is suitable for transient simulations of packaging interconnect systems.

Electromagnetic Simulation for Inhomogeneous Interconnect and Packaging Structures

The paper contains a novel mechanism for full wave electromagnetic simulation of complicated inhomogeneous structures, such as on-chip interconnects, IC packaging, antennas, and scattering objects. It uses only equivalent principle based EFIE instead of both EFIE and MFIE to establish the surface integral equations for practical inhomogeneous structure so that a much more simplified formulation process is needed in the EM simulation procedure. To overcome the numerical error of K operator in the formulation, a new analytical solution to the K operator for general full-wave integral equations is provided. Numerical results are demonstrated to verify the proposed algorithm.

Techniques and considerations for verification of model causality

High data switching rates of todays computer architecture continue to intensify the need for transmission line modeling accuracy. As these data rates exceed hundreds of megahertz and the physical complexity of the transmission channel increase, it may no longer be sufficient to ensure only the frequency dependency of channel models. Rather, the model developer must guarantee the model response is passive and causal. This is of particular interest given that non-causal models may not allow convergence or yield accurate channel loss within industry-standard tool suites, even though its response may yield reasonable correlation to measured scattering parameters. Therefore, model developers must understand how the model creation, checking and simulation tools work together to ensure validity of transient simulations. Commercially-available tools exist that provide numerical and visual interpretation of causality compliance (or violation) for any given touchstone model. It is critical, however, for the model developer to understand the verification process used within a chosen tool suite and how to interpret results. Moreover, model developers must know how model frequency content, step size, length and other parameters may impact a checking tools ability to accurately flag causality violations. As a result, the developer must have an in-depth understanding of the correlation between model content and causality error reporting, whether or not violations raise real concerns and if so, how they may impact the results obtained from the system-level simulation methodology. This paper will discuss the interaction between the model development process, the ability to verify model causality and the impact at the link or system-level as a result of non-causal models or inaccurate interpretation of causality-checking verification tools.

An analysis on measurement sensitivity of Short-Pulse Propagation technique using a virtual test bench

This paper presents the concept of using a virtual test bench to emulate measurements via simulation and modeling. For demonstration purposes, this idea is used to quantify the measurement sensitivity of the short-pulse propagation technique to the line parameter tolerances found in production level circuit boards without building the hardware. This method is applicable to other measurement methodologies such as in the calibration and de-embedding steps of frequency-domain characterization.

Parallelization of the Reduced-Coupling Technique for a Method-of-Moments-Based Field Solver Used for Product-Level Wide Data-Bus Analysis

A parallel LU decomposition algorithm is presented to take advantage of the sparse impedance matrix produced by the reduced-coupling method. This algorithm allows rapid simulation of very large chip and packaging problems. A representative example is shown for a wide, on-chip data-bus that required one million surface unknowns and the computational power of a 1024-node IBM BlueGene cluster with distributed memory.

The Use of Accelerated Full-Wave Modeling to Analyze Power Island Coupling in a HyperBGA SCM

Presented here are results and recommendations for reducing coupling between adjacent power islands based on full-wave simulations of a HyperBGA SCM (single-chip module). These simulations highlight the use of IBMs internally developed accelerated full-wave solver based on the precorrected fast Fourier transform approach. Speedups of 100times and memory reductions of 12times are shown for real engineering problems, as compared to direct integral equation solutions