Nonlinear modeling and model-validation for digital switched mode RF power amplifiers

In this paper a methodology for identifying broadband nonlinear models for digital switched mode RF power amplifiers is presented. This can be accomplished by training a black box model by observing an amplifier´s output waveform in time domain. It is demonstrated that the presented method is feasible for using a simple and relatively short excitation sequence. The required model-complexity for a given amplifier is unknown in general, therefore, a testing method is presented in order to select a model of sufficient complexity. This is necessary since selecting a model solely on how well it reproduces the training sequence has been proven not to be sufficient. A digital power amplifier lab-setup serves as test platform in order to verify the validity of the so derived model.