Simulation of Linear and Nonlinear Circuits for Symbolic Analysis and Transient Response

For pedagogical reasons, classroom examples of analysis are usually performed symbolically. A student can frequently attain insight as to the relative effects of various circuit elements when they have symbolic labels. A prototype program has been devised which is capable of determining symbolic equations for a class of circuits. The equations are written in FORTRAN type notation. Although the original intention of the program was to determine circuit state equations, several other applications exist. For instance, dc analysis, such as that which is required for steady-state analysis, may be performed. If a circuit is linear, it is possible to obtain a transfer function for which the s polynomial coefficients are symbolic. Transient responses often yield information which is not discernible from symbolic relationships. For this reason, a companion program which integrates the state equations determined by the preceding program has been written. Currently, the integration routine must be run separately by the user. This entails the insertion of the state equations and other integration control statements. It is believed that a program which relieves the user from this task will be available by the time this paper is published. Numerical examples are also included in the paper.