A historical review of circuit simulation

Within the Circuits and Systems (CAS) Society, developments in computer-aided circuit analysis and circuit design commenced in the early 1950's using the earliest digital computers. Initially, computer-aided circuit analysis of linear circuits was used in design optimization, design centering, and in determining the effects of parasitics on circuit performance. Although this use of computer-aided circuit analysis has continued, computer-aided design (CAD) and circuit design automation within the CAS Society are now principally concerned with problems associated with the overall design and evaluation of very large circuits and systems. This paper is a review of a major thread of CAD activity which has occurred within CAS from the earliest and remains of major interest. This thread involves computer-aided circuit analysis (circuit simulation) and its use in CAD systems. Fortunately, several excellent review papers have appeared within the past year or two to document well the technical milestones, as well as the problems of interest at the present time. It is possible then, in this paper, to concentrate on the developments in our present capability of circuit simulators, stressing the significant trends, noting some early developments which did not become major aspects, and observing the interchange between theory and practice.