An algorithm for eliminating false intermods from the intermodulation spectrum computed for a nonlinear amplifier

This paper describes an algorithm for making corrections to a new model for computing intermodulation spectra of arbitrary order for a nonlinear amplifier with specified amplitude and phase characteristics. Known as the joint occupancy algorithm (JOA) model, the new model is computationally much simpler than previous approaches. Furthermore, the complexity is virtually independent of the number of input signals and the order of the intermodulation spectra to be computed. However, when the number of input signals is small, the presence of false intermods causes significant distortion in the computed intermodulation spectrum. This paper introduces an algorithm for eliminating these false intermods. It is shown that the resulting corrected spectra exhibit excellent agreement with the spectra computed by more traditional methods.