An efficient procedure is described for the simultaneous characterization of both the time and frequency domain behavior of electromagnetic devices. Starting with a full-wave electromagnetic analysis based on either the finite element or boundary element method, a reduced order frequency domain model is generated for the electromagnetic system. Two different methods are used to compute the reduced order model: (1) Asymptotic Waveform Evaluation (AWE) or (2) Adaptive Lanczos-Pade Sweep (ALPS). The reduced order electromagnetic model is used to generate a stable equivalent electrical circuit that may be used in a circuit simulator to generate the transient response of the device, either alone or as part of a larger system. Examples will be presented demonstrating the implementation of this procedure in Ansoft's commercial software.