Model Parameterization of Nonlinear Devices Using Impedance Spectroscopy

In this paper, a new approach is used to identify the parameters of a large-signal lumped-element model for nonlinear devices based on small-signal impedance measurements at several operating points. Starting from the large-signal impedance of an equivalent circuit with nonlinear devices, the relationship between current and voltage is derived by the determining nonlinear system equation. This differential equation for a first-order model is then linearized via nonlinear series expansion using the perturbation approach. The linearized ac part (which is the fundamental frequency part) is then transformed into the frequency domain to find a representation of the complex small-signal impedance for a given operating point. Large-signal modeling based on small-signal measurements is successfully demonstrated for organic light-emitting diodes.