In a method of characterizing a circuit, a test sequence is provided A response of the circuit to the test sequence is determined A transfer function that corresponds to the response is determined The transfer function is decomposed into a plurality of terms A respective term corresponds to an nth-order term in an expansion of at least 3rd order that corresponds to the transfer function A characteristic associated with the circuit is simulated using at least one of the terms in the plurality of terms Figure 1 is a block diagram illustrating an embodiment of a system.