Supply and ground variation due to switching noise is an important issue in digital and mixed-mode integrated circuits. An approach for calculating the supply and ground bounce is presented in which the effects of parasitic elements of package and bond wires are considered. The proposed method leads to a system of linear equations whose analytical solution can be used to predict the behavior of supply and ground variations. SPICE simulations are used to verify the accuracy of the approach. The importance of modeling package parasitics and the dependence of switching noise on parasitic elements are also discussed.