Computation of DC Solutions for Bipolar Transistor Networks

The dc state vector is often the desired initial condition for the solution of a system of first-order differential equations that characterize network dynamics. A computer algorithm is described in this paper that computes the dc solution of first-order differential equations that characterize networks containing transistors, diodes, capacitors, inductors, resistors, and voltage sources with neither cut sets nor closed loops of either junctions, capacitors, or inductors. Networks containing current sources were not considered. The Newton-Raphson iteration function is the basis of the dc solution algorithm. The unique feature of the solution procedure is the use of upper bounds on the solution to avoid slow convergence and difficulties in computing exponential functions. Derivation of the upper solution bounds is discussed in detail.