Hansruedi Heeb

Circuit models for three-dimensional geometries including dielectrics

The partial element equivalent circuit (PEEC) approach has proved useful for modeling many different electromagnetic problems. The technique can be viewed as an approach for the electrical circuit modeling for arbitrary 3-D geometries. Recently, the authors extended the method to include retardation with the rPEEC models. So far the dielectrics have been taken into account only in an approximate way. In this work, they generalize the technique to include arbitrary homogeneous dielectric regions. The new circuit models are applied in the frequency as well as the time domain. The time solution allows the modeling of VLSI systems which involve interconnects as well as nonlinear transistor circuits. >

Three-dimensional interconnect analysis using partial element equivalent circuits

Two extensions to the partial element equivalent circuit (PEEC) approach for interconnect modeling are presented. First, retardation, the effect of the finite speed of electromagnetic interactions, is included. Second, PEEC is extended to include a circuit model of finite-size homogeneous dielectrics. It is shown that the retarded PEEC formulation with the new dielectric model is equivalent to a full-wave solution of Maxwells equation. Since they can be combined with linear and nonlinear circuits, the resulting models are more flexible than existing full-wave solvers. >

Stable time domain solutions for EMC problems using PEEC circuit models

Time domain solutions for electromagnetic problems are important for many EMC applications like ESD and integrated circuit EMI. The most common solution formulation for such problems is based on integral equations. The instabilities in the solution associated with integral equation techniques in the time domain are well known. In this paper we show that the instability may be either due to the numerical technique used for the time integration or due to problems created by the discrete representation for the solution of the problem by the numerical integration technique. We use the Partial Element Equivalent Circuit (PEEC) formulation of the EFIE integral equation for small model problems and some popular integration techniques to give specific examples of instabilities in the time domain solution. Importantly, we introduce techniques which lead to stable results.<<ETX>>

Stability of discretized partial element equivalent EFIE circuit models

The instabilities associated with integral equation techniques for-the solution of electromagnetic problems in the time domain are well known. Instabilities may be due to either the numerical technique used for the time integration, or problems created by the discrete representation for the numerical solution of the problem. In this paper, we concentrate on the discretization issue. The stability problem occurs for various discretizations and formulations. Here, we use the partial element equivalent circuit (PEEC) formulation of the electric field integral equation (EFIE) in the circuit domain. This leads to a better understanding of the issues at hand. We show why the discretized model can be unstable and we suggest a circuit motivated technique to stabilize the solution. >

Retarded models for PC board interconnects-or how the speed of light affects your SPICE circuit simulation

It is shown that retardation effects, due to the finite speed of electromagnetic interactions, play a significant role for PC-board interconnects. It is demonstrated that in some cases errors of more than an order of magnitude result in some frequency components when retardation is neglected. Extensions to a circuit simulator are introduced that make it possible to do retarded circuit simulation. Specifically, an algorithm to extend SPICE-level simulators to include retardation is presented. Comparisons with analytical equations, the method of moments, and with measurements show good agreement.<<ETX>>

Simulating 3-D retarded interconnect models using complex frequency hopping (CFH)

With ever increasing clock frequencies, accurate 3-D interconnect analysis in chips and packages is becoming a necessity. The retarded partial element equivalent circuit (rPEEC) method has been successfully applied to 3-D analysis but for large problems it becomes expensive in CPU and memory usage, and in time domain it sometimes has numerical problems. Complex frequency hopping (CFH), a new multi-point moment-matching technique, is expanded to handle retarded networks. CFH speeds up rPEEC frequency domain analysis of large frequency bands significantly. It also allows the efficient calculation of resonances and - most importantly - enables time domain modeling of rPEEC networks that have so far resisted analysis by any other method.

On the effectiveness of decoupling capacitors in reducing EM radiation from PCBs

The effectiveness of using decoupling capacitors (decaps) between power and ground planes in a typical PC or workstation printed circuit board (PCB) is studied from an electromagnetic-compatibility (EMC) point of view. By examining the radiation from the board, the effects of the total number of decaps, the placement of decaps, and lead inductances are investigated. The novelty of the present studies is that they focus directly on electromagnetic radiation as opposed to the more traditional investigation of decaps by only examining their equivalent impedances.<<ETX>>

A fast method for computing radiation from printed circuit boards

An alternative approach for computing radiation from a multilayer circuit board is presented. Compared to a full-wave electromagnetic approach, this method is much faster and requires less storage space for data. Computational efficiency is the key attribute of the approach. It allows solutions, previously unobtainable, to complex and realistic structures, such as those arising from typical product designs. The radiation is calculated using a transmission line model to find the amplitude and spatial distribution of currents in printed circuit traces. The far field is computed using the Greens function of a current element just above, or inside, a thin dielectric sheet. Two examples are considered: (1) a comparison of results in the frequency domain obtained by using the method described here with those of a full-wave electromagnetic approach based on the method of moments; and (2) a comparison of simulation results with real semianechoic chamber measurements.<<ETX>>

Methodology for evaluating practical EMI design guidelines using EM analysis programs

Most companies oflering products that mus t pass FCC or’ other regulatory agency specifications have compiled EMI design guidelines which are practiced b y their engineers. I n this paper, we take one such practical E M I design guideline and, through extensive use of a state-of-the-art electromagnetic analysis code, investigate its range of applicability, and show its lamitations. The emphasis is placed on the methodology, rather than the guideline itself, so that a framework is established under which other EMI design guidelines can be similarly “revisited”.

Frequency Domain Microwave Modeling Using Retarded Partial Element Equivalent Circuits

Full-wave electromagnetic modeling is used increasingly to model the properties of high speed interconnect or to predict electromagnetic interference. Retarded partial element equivalent circuit (rPEEC) models provide a way to simulate with full-wave accuracy in time and frequency domain without leaving the level of circuit simulation. This paper presents a new algorithm to simulate frequency domain rPEEC models efficiently.