Copyright
by
Emre Tuncer
1995
by
EMRE TUNCER, B.S.E.E., M.S.E.E.
DISSERTATION
Presented to the Faculty of the Graduate School of
The University of Texas at Austin
in Partial Fulfillment
of the Requirements
for the Degree of
DOCTOR OF PHILOSOPHY
THE UNIVERSITY OF TEXAS AT AUSTIN
December 1995
Designing digital systems with clock rates over 100MHz and sub-nanosecond rise and fall times requires not only a state-of-the-art processing technology but also a good understanding of pulse propagation through complex interconnect structures with lossy conductors. Due to the wide frequency bandwidth of digital signals, frequency dependent characteristics of interconnects should be obtained accurately. For designers, considering the complexity and the size of the problem, full-wave electromagnetic solutions are not acceptable due to computer time and memory requirements. This dissertation presents an efficient methodology to extract series impedance of interconnect structures which is suitable to be integrated into CAD tools.
First a quasi-static model for interconnects on silicon substrate is developed to calculate parameters for all the three modes that this structure supports, namely slow-wave, quasi-TEM, and skin-effect modes. Representing internal behavior of conductors at their surface by an effective internal impedance calculation simplifies the solution and saves computer time that would otherwise be used to calculate fields inside the conductors. Coupled to an external solver, the effective internal impedance is a powerful approach to solve two dimensional quasi-static problems. The effective internal impedance approach is then applied to the conformal mapping technique and a modified filament technique. Using conformal mapping, extraction of series impedance for two dimensional structures for a wide frequency range is very fast and accurate once the map has been found. Although conformal mapping is efficient, mapping multi-conductor interconnect structures is arduous. A modified filament technique, using surface ribbons and effective internal impedance is shown to be very efficient for two dimensional multi-conductor interconnect structures that can be found on multichip modules and circuit boards. The surface ribbon and effective internal impedance approach, being accurate, fast, and memory efficient, is very suitable to be integrated with CAD tools.
Links are to PDF versions of the original dissertation. To obtain a "fair use" copy of the material via the WWW send e-mail to Professor Dean Neikirk (neikirk@mail.utexas.edu) requesting the user name and password required to download the files. This material is not to be re-published in any form, electronic or otherwise, without permission of the copyright holder.
Chapter 1, Introduction p. 1
Chapter 2, Transmission Lines on Lossy Substrates p. 6
Chapter 3, Effective Internal Inductance p. 22
Chapter 4, Conformal Mapping p. 40
Chapter 5, Surface Ribbon Technique p. 63
Chapter 6, Conclusions p. 78
Appendices, p. 81
Appendix A, Non-uniform Transmission Lines p. 82
Appendix B, Mutual Inductance of Ribbons p. 86
Bibliography, p. 89
Vita .