CAD-based electric-circuit modeling in industry. I: Mathematical structure and index of network equations (Q1288813)

This is the first of two articles discussing modeling and numerical aspects in the simulation of electric circuits [for the second part see ibid. 8, No. 2, 131-157 (1999; reviewed below)]. It starts with a brief survey of the typical elements found in such circuits, of the basic equations governing their behaviour and of schemes for setting up the complete network equations. After a short look on the mathematical structure of these equations, it is shown how refined modeling which takes care of a number of parasitic effects affects the index of the system. As example a bipolar ring oscillator is studied. Much emphasis is put on clarifying the relation between the classical network theory with voltages and currents as basic variables and a charge/flux oriented approach.