  In this paper the concept of Multirate Partial Differential Equations (MPDEs)
is applied to obtain an efficient solution for nonlinear low-frequency
electrical circuits with pulsed excitation. The MPDEs are solved by a Galerkin
approach and a conventional time discretization. Nonlinearities are efficiently
accounted for by neglecting the high-frequency components (ripples) of the
state variables and using only their envelope for the evaluation. It is shown
that the impact of this approximation on the solution becomes increasingly
negligible for rising frequency and leads to significant performance gains.
