Analytical Modeling of a Class of Microstrip like Interconnects

Abstract

In this thesis, I present the analytical modeling of a class of microstrip-like interconnects commonly used in the MCM environment. These interconnect lines are characterized using the variational method combined with the transverse transmission line technique. The major parameters modeled in these interconnect lines are the characteristic impedance, delay constants, signal overshoots, ringing and crosstalk. The conventional microstrip form is modified and analyzed by introducing alteration in the way the ground plane is represented with respect to the unbalanced feeding line. The analysis attempts to predict accurately the signal integrity issues arising out of such modifications. The type of interconnects analyzed in this work include single and coupled microstrip lines with adjacent ground tracks and lines with an aperture in the ground plane below the line. The analytical models developed in this newlinethesis retain the robustness and simplicity of the variational method, which has been elaborated in the previously published literature. Results are confirmed by a commercial and accurate field simulator and verified by systematic measurements performed using a vector network analyzer. newline newlineFour interconnect structures with specific geometry have been studied in this work. These include a microstrip line guarded by ground tracks on either side, a coplanar interconnect line, microstrip line with partially removed ground plane below the line, and coupled microstrip lines with intermediate ground track insertion. The applications of these interconnect structures are quite common in VLSI, RF, MCM, and PCB design. Elaborate design data is provided in the appendices which may aid practicising engineers and designers. Also, various empirical formulae have been worked out for the characteristic impedance of these interconnects. The work reported in this thesis concludes in form of a software tool, FastEx, which aids in fast and accurate computation of various design parameters. newline newline