Modeling of nonlinear active and passive devices in three-dimensional TLM networks
Date
2017-06-07
Authors
Cascio, Lucia
Journal Title
Journal ISSN
Volume Title
Publisher
Abstract
The increase in clock rate and integration density in modem IC technology leads to
complex interactions among different parts of the circuit. These interactions are poorly
represented with traditional lumped circuit design methodologies. Traditional CAD tools,
such as SPICE, provide very accurate models for a large variety of active devices, but
their description of the passive part of the circuit is progressively becoming insuffcient,
as the frequencies of the signals increase. Problems such as dispersion, crosstalk and
package effects require a full electromagnetic approach in order to predict their impact
on the final response of the circuit. On the other hand, the application of a full-wave
numerical method for the analysis of a complete device containing nonlinear elements is
not sustainable with the present computer capabilities. The spatial and time discretization
steps required to accurately model the nonlinear part of the device are much smaller than
those necessary to describe the distributed part of the circuit.
In the present thesis, the possibility of modeling nonlinear devices with the three-dimensional
TLM method has been explored; a new procedure has been successfully
developed and implemented, linking the equivalent circuit representation of the nonlinear
device to the transmission line model of the electromagnetic fields in the TLM network.
No restrictions are applied on the size of the device, which can thus occupy more
than a TLM cell. In order to model devices embedded in heterogenous media, a modification
of the TLM node and relative scattering matrix has also been proposed. In view of
linking the TLM field solver with a lumped element circuit CAD tool, the modified TLM
scattering algorithm has remained independent of the specific device connected to the
mesh.
The general methodology shown in this thesis appears to be a promising approach
to solve a large variety of electromagnetic problems containing nonlinear elements.
Description
Keywords
Electromagnetic theory, Nonlinear functional analysis, Microwave transmission lines