D-C and transient analysis of networks using a digital computer

Abstract

An experimental program is described for computing the d-c and transient response of transistor switching circuits of arbitrary configuration and size (up to 20 transistors) using the IBM 704 computer. One important feature of the program which is discussed is its ability to compile all the necessary equations automatically from input data describing the circuit parameters and configuration. Another is the solution of the transient problem by numerical integration OS the differential equations for the linear part of the circuit separately from those describing the transistors , the output from each set of equations being used periodically as input for the other set. Con-sidcrable increase in speed of integration is obtained in this manner, The method of d-c analysis is based on a topological-matrix formulation of the linear part of the problem. and its solution by Kron's method, followed by an iterative procedure for satisfying certain nonlinear side conditions imposed by the transintors. Although the transient analysis also uses a matrix formulation of the required differential equations, it is not based on a topological approach. However, a generalized topological-matrix formulation of the transient problem is given in an appendix. The nature of a serious theoretical limit on the rate of integration of the network equations. is discussed since it constitutes the principal computational barrier to a rapid solution of the transient problem. An outline of the tnore important programming procedures involved in the topological-matrix formulation is also given. Certain shortcomings of the program, and pitfalls to be avoided are pointed out. In particular , the importance of being able to modify or replace the transistor equivalent circuit (network model) is emphasized. Finally, the computed responses of a four-transistor switching circuit are displayed and shown to agree well with the observed responses, Int reduction This paper is based on the experience gained in writing an experiental program for analyzing transistor switching circuits using the IBM 704 computer. Thin program, called TAP for " transistor analysis program " , 102 was developed to provide circuit-design engineers with the ability to carry out " computational experiments " to aid in understanding, as well as designing, switching circuits. Although this objective was reached, the program has become obsolete because it was restricted to the analyeis of circuits containing a certain type of diffused base transistor which is of limited interest. Consequently, the program is not being maintained nor is it being made available for …