1. A method of creating an equivalent model for an integrated circuit (IC) and package, the IC including a plurality of input/outputs (I/Os), the method comprising the steps of: generating an intermediate model by partitioning the IC into a plurality of simulation windows having a substantially similar characteristic; converting I/Os within each simulation window to a current source; and generating the equivalent model for at least one simulation window based on an observed current change rate of the simulation window during a simulation.