Dependent Source Modeling For Spice

While the SPICE circuit analysis program is commonly used for solving pulsed power circuit problems, it lacks convenient models for nonlinear devices and mathematical functions. This paper will describe the use of dependent sources to implement several of the devices and math functions that am of frequent interest to the pulsed power engineer. SPICE has dependent sources, representing transconductance, voltage gain, current gain, and transresistance. These sources can be used to model devices like switches and non-linear resistors, and to perform mathematical exercises like addition, subtraction, multiplication, etc. When combined with simple circuits it is also possible to integrate and differentiate voltages and currents at any point in the circuit. By using a variety of these models, it is possible to obtain complete circuit and component diagnosis. For example a switch could be characterized for di/dt, dv/dt, coulomb transfer, action integral ( /spl int/i/sup 2/dt ), and peak power, while a load element could be be monitored for temperature rise, etc. The possibilities are limited primarily by imagination.