1. A method for determining a model network of nonlinear circuitry having an input and an output, the model network comprising one or more static nonlinear elements and a plurality of linear filters with transfer functions, comprising: performing an input amplitude-to-output amplitude measurement of the nonlinear circuitry, performing an input amplitude-to-output phase measurement of the nonlinear circuitry, and calculating the transfer functions of the linear filters on the basis of results of the input amplitude-to-output amplitude measurement and input amplitude-to-output phase measurement.