A flexible algorithm for solving systems of circuit differential-algebraic equations with integrated Fortran 95 compiler for modeling

Although many simulation tools contain advanced algorithms for the solution of the systems of differential-algebraic nonlinear equations, some classes of circuits still cause serious problems. In the paper, a very flexible and reliable algorithm for solving the circuit differential-algebraic equations is characterized first, which is based on a sophisticated arrangement of the Newton interpolation polynomial. After that, a reliable method is introduced for improving the convergence with four possible criteria. Unlike the similar algorithms focused on an operating point analysis only, the proposed method also works in a transient analysis. Moreover, for an ability of the procedure to model practically arbitrary electronic device, a subset of the Fortran 95 programming language was integrated to the circuit simulator with a power to differentiate functions symbolically.