Simulation and Modeling Techniques for Signal Integrity and Electromagnetic Interference on High Frequency Electronic Systems. by

Simulation and Modeling Techniques for Signal Integrity and Electromagnetic Interference on High Frequency Electronic Systems. by Luca Daniel Doctor of Philosophy in Engineering Electrical Engineering and Computer Sciences University of California at Berkeley Professor Alberto L Sangiovanni-Vincentelli, Chair Many future electronic systems will consist of several significantly heterogeneous modules such as OptoElectronic and analog RF links, mixed-signal analog to digital converters (ADC), digital signal processors (DSP), Central Processor Units (CPU), Memory modules, Microfabricated Electro-Mechanical (MEM) resonators, sensors and actuators with power electronics converters. When assembling such an heterogeneous set of modules on a single package (Systems on Package: SoP) or integrated circuit substrate (Systems on Chip: SoC), compatibility issues are soon to arise from many possible point of views. In this thesis, we will address the physical electromagnetic point of view. We aim to encompass phenomena that range from the well known electric field capacitive cross-talk, to the more challenging magnetic field inductive coupling, and even full-wave propagating electromagnetic field couplings. We find the standard approach to ElectroMagnetic Compatibility (EMC) used on Systems on Board (SoB) quite inappropriate for Systems on Chip (SoC) where prototyping, metal shielding and ground planes are often expensive, and sometimes completely impractical. In the first part of the thesis we propose instead an accurate and efficient three dimensional electromagnetic field solver as a valuable tool for verifying the design against all sorts of electromagnetic interference before fabrication. In the second part, we propose modeling techniques as a valuable tool for characterizing each module with respect to its electromagnetic properties, so that higher level circuit simulators can be used effectively to check the compatibility of different blocks. In the third part of the thesis we argue that compatibility should be achieved through an automatic interconnect synthesis process, enabled by our newly developed parameterized modeling technique. The new generation of fast electromagnetic analysis programs, based on accelerated integral equation methods, has reduced the time required to analyze thousands of simultaneously interacting conductors from days to minutes. However such solvers are either inappropriate for, or are very inefficient at, analyzing interconnect exhibiting high frequency effects. With processor clock speeds exceeding two gigahertz and harmonics exceeding twenty gigahertz, high frequency effects cannot be ignored. The effects that are most troublesome for fast solvers are skin and proximity effects. Such phenomena can significantly affect interconnect performance and should not be neglected, in particular when either wire width or thickness is greater than two “skin-depths.” Interconnect performance on Printed Circuit Boards (PCB) and on IC Packages has suffered from such effects for many years. Even some Integrated Circuits are now starting to be affected at the global interconnect level (power, ground and clock distribution networks). For instance skin-depth in aluminum interconnect at the tenth harmonic of a two gigahertz clock is around a half micron. Skin and proximity effects are troublesome for current fast solvers because they generate an exponentially varying current distribution inside each conductor. Trying to represent that current variation using the standard piecewise constant basis functions commonly available in fast solvers requires a large number of unknowns. Since the computation time for fast solvers is supposed to increase only linearly (more precisely O(nlog(n))) with the total number n of basis functions used in the problem, it may seem that the increase in unknowns to represent current variation is not that problematic. However, when many basis functions are used to represent