UCSC-CRL-92-11: OPTIMAL DESIGN OF SELF-DAMPED LOSSY TRANSMISSION LINES IN A TREE NETWORK FOR MULTICHIP MODULE

04/01/1992 09:00 AM
Computer Engineering
This paper addresses some of the problems encountered in propagating high-speed signals through lossy transmission lines on the substrates of silicon-on-silicon thin-film multichip modules (MCM). Instead of terminated by resistors, the lossy lines on the thin-film multichip modules can be structured to critically damp out the signal resonances, they are thus called *optimal, self- damped lossy transmission lines*. It is easiest to manufacture interconnection lines with fixed metal and dielectric thicknesses, and vary only the line width. This results in specific dependency of line width on length for self-damped lines. In this paper, we present the a simple and robust method of designing self-damped lossy transmission lines in a tree network for multichip module. We vary the width of each branch of the network to meet certain electrical damping criteria. This results in stable operation as long as the lossy transmission line is shorter than the quarter wave length of the highest frequency component of interests. The lengths of lines on the silicon-on-silicon thin-film MCM substrate usually does not exceed this limit. If certain designs require larger substrate or higher speed, the materials and structural properties of the substrate (for example the dielectric thickness) is changed according to the method.

UCSC-CRL-92-11