Measuring nonlinear devices to retrieve good system-level models

Abstract

The quality of a system-level model for a non-linear component strongly depends on the used measurement approach, especially for power amplifiers. Several measurement approaches exist for all sorts of high-level models, but they often do not take into account the power spectrum of the modulation scheme used. This discrepancy is a major drawback since the output of nonlinear systems strongly depends on the power spectrum of the input. A system-level model based on the best linear approximation overcomes this disadvantage, but so far, no suggestion was made for a measurement setup. This paper clarifies a measurement approach to retrieve the components of the model based on the best linear approximation. This measurement approach uses excitation signals which closely resemble the actual excitation signal of the device. It results in good system-level models for both weakly and strongly nonlinear systems. Furthermore, this approach can be used in nearly every RF measurement facility.