A method of predicting the electromagnetic noise emitted by a digital circuit on an integrated circuit is disclosed. In accordance with the illustrative embodiment, the output of each digital circuit element in the digital circuit is considered as a bit stream. All of these bits streams are, in aggregate, considered as a noise source that is characterized by a power spectral density, S(). The effect of the noise source on an analog circuit can be modeled as a lumped circuit, wherein the lumped circuit contains a noise source that represents the digital circuit; a multi-port network, also referred to as a lumped element, that represents that portion of the substrate between the digital circuit and the analog circuit; and a multi-port network that represents the analog circuit.