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The design and development of computer models to simulate analog devices and their effects on circuit applications has been investigated at length. The focus of this research is the development of theoretical and computer models for discrete devices using the popular simulator PRECISE, PRogram for Evaluating Circuits in an Interactive Simulation Environment [3], using a new method for model construction. This new method develops a model approximating the mathematics of the simulation via perturbations and iterations [19]. The models developed by the new method in each case yield a minimum simulation accuracy of 90 percent in circuit applications. In comparison, models developed by the conventional method, which uses measured data to complete physical constructs of SPICE 2G.6 [5], offer a lower accuracy for the same circuits. Hence, the new method is more effective than the old method and also much faster, since the model generation process is now automated and does not require time-consuming manual measurements and calculations spread out over a long period of time. With further development, a computer model can also be developed for the theoretical model presented in this thesis for the Gallium Arsenide Metal Semiconductor Field Effect Transistor (GaAs MESFET) device using the same methodology that has been used to develop the computer model for the Bipolar Junction Transistor (BUT) device. Hence this research, in addition to developing a library of a hundred and fifty odd successful models in the PRECISE and SPICE formats for the diode and BUT, can also be used to develop a new model for the GaAs MESFET, which would make both PRECISE and SPICE easier and more user friendly as circuit simulators. / Master of Science

In order to simulate the Schottky Transistor and its effect on circuit applications, a computer model has been developed for the device. The focus of this research is the development of such a model for SPICE2 (a circuit simulation computer program) using a new method for model construction. This new method developes a model by approximating the mathematics of the simulation via perturbations and iterations. The model developed by the new method yields a minimum simulation accuracy of 65% in a variety of circuit applications. In comparison, a model developed by the conventional method, which uses measured data to complete the physical constructs of the SPICE2 model, offers the same margin of accuracy for the same circuits. So the new method is just as effective as the old method for the circuits that were tested. Yet with further development, the new method for model construction can be automated eliminating the time consuming and possibly inaccurate measurements of the old method that would discourage the use of SPICE2. So this research, in addition to developing two successful SPICE2 models for the Schottky Transistor, also introduces a new method for model construction that can make SPICE2 easier to use. / Master of Science