Simulation of Hybrid Circuits based on Beyond-CMOS Technologies

Because of the ever-so-complex challenges posed by Silicon in continuing the trend of constant evolution that has characterized electronics for the past few decades, in the recent years researchers have been increasingly interested on developing new and promising technologies that can overcome the current CMOS scaling limits and possibly offer unique features. These technologies are referred to as "Beyond CMOS" technologies as they employ innovative materials and techniques to construct digital circuits. On account of the scattering in popularity and the development stage of the many candidates of this field, the world of simulations is heavily fractured: the more popular entries already feature custom simulators, some simply offer models compatible to other existing simulators, others only come with mathematical models. The objective of this thesis is to develop new tools to build a generic Hybrid Simulator, a simulator not only able to support arbitrary technologies given the right models, but also to handle circuits hosting more of these technologies that coexist in the same design. The presented work was developed as an extension of the ToPoliNano framework with the objectives of generality, customizability and ease of integration. The first necessary step was to extend MagCAD to allow the user to design hybrid circuits. Accordingly to the program structure I developed the Hybrid Plugin, a plugin providing the interface and all the additional tools needed to place and interconnect components designed in MagCAD featuring arbitrary technologies. On top of this, the new plugin also supports the insertion of custom VHDL or Verilog netlists in the design to represent classical CMOS digital components or testing facilities. In order to run the simulations managed by ToPoliNano, the choice fell on offloading the work to ModelSim, an established and feature-rich simulator. This is because not only does ModelSim have extensive and thoroughly tested support for VHDL, Verilog, VerilogA and much more, but also because of its interesting Foreign Language Interface (FLI). This feature offers a C API through which the user can interact with the simulation and insert his own custom models developed in C. To simplify the interaction with ModelSim and to adapt it with the modern standards, a small C++ library called flipp was also developed. It adapts the most relevant features from the FLI to C++ and adds some useful wrappers and helpers and it can be used when designing custom models. Finally, I developed a module to be inserted into ToPoliNano offering a set of useful classes to build custom C++ models based on flipp plus the necessary infrastructure to manage and interact with the simulation. The result of this work is a rich, fully customizable and easily extensible system which enables the user not only to define or import models with varied descriptions (VHDL, Verilog, VerilogA, C++), but also to freely design and simulate hybrid circuits where more of these models are interconnected.