Characterizing Amplifier Modulation Distortion Using a Vector Network Analyzer

This paper describes a method to characterize signal distortion caused by amplifiers under modulated operating conditions. The method is based on decomposing the output signal into one part that is linearly correlated with the input signal, and another part that is the nonlinear distortion. The decomposition is based on calculating the statistical cross-correlation between the spectra of the input and the output signal. The measurements are performed using a vector network analyzer. The input signals are repetitive and can be designed to match the statistical and spectral characteristics of any given modulation format.