Using x-parameters for signal integrity applications

X-parameters, the nonlinear extension of scattering parameters, have been shown to have a wide array of applications in the modeling of nonlinear devices and systems. In this dissertation, the use of X-parameters is extended to signal integrity applications, particularly to the modeling of input/output buffers. These input/output buffers are the nonlinear terminations of the high-speed links that the signal integrity engineer is tasked with designing and optimizing. Brief treatments of the X-parameter formalism, the harmonic balance simulation method, the latency insertion method, and the Input/Output Buffer Information Specification (IBIS) are provided as background information along with some examples of how X-parameters are generated via simulation and measurement and used in simulation. Two processes for using X-parameters for signal integrity purposes, lim2x and x2ibis, are described and analyzed in detail. The process lim2x uses the latency insertion method to perform a transient simulation of a given circuit with specific port stimuli and terminations. It then uses Fourier analysis to extract X-parameters from the simulation results. This process leverages the linear numerical complexity of the latency insertion method to provide a viable X-parameter generation platform that is well-suited for very large, high-frequency circuits, particularly those which are seen in input/output buffers. The lim2x process is demonstrated on a simple buffer circuit. The X-parameters generated from it are compared to those generated with harmonic balance and are shown to be in excellent agreement. IBIS models are the current standard for modeling input/output buffer circuits. The process x2ibis uses X-parameter models to generate the current-voltage and voltage-time tables used in an IBIS file. This process shows that properly generated X-parameter models contain the information needed to describe the behavior of an input/output buffer. Results are compared with those of another method of IBIS model generation.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Electrical & Computer Engr

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2014

Author dc:creator

• Comberiate, Thomas M.

Contributors dc:contributor

• Schutt-Ainé, José E.
• Bernhard, Jennifer T.
• Cangellaris, Andreas C.
• Franke, Steven J.

• X-parameters
• signal integrity
• Latency insertion method (LIM)
• high-speed link
• nonlinear vector network analyzer

Statement dc:rights

• Copyright 2013 Thomas Matthew Comberiate

Language dc:language

en

Handle dc:identifier

http://hdl.handle.net/2142/46714

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/46714