EMC (Electromagnetic compatibility) spec criteria in Volterra systems

Identification of nonlinear transfer functions (NLTF) and their use in predicting electromagnetic compatibility (EMC) specification parameters such as intermodulation and harmonic distortion was studied. It was assumed that the nonlinear systems of interest can be modeled as lumped parameter circuits with zero-memory nonlinearities between circuit nodes. In this case, the NLTF poles are determined by the poles of the linear transfer function (LTF) of the circuit. Two different cases were considered. In the first case, a transient response measurement of the LTF output can be used to identify the linear system poles. The poles of the LTF then specify the poles of the NLTFs. In the second case, the received signal contains a strong direct path component which is independent of the nonlinear system which is to be identified. This situation arises in the identification of the rusty bolt (a Metal-Insulator-Metal junction). Under this condition, the rusty bolt linear response cannot be measured directly and it is then necessary to estimate the poles of both the LTF and NLTFs from sinusoidal steady state third-order nonlinear response measurements.