Envelope Distortion Models with Memory Improve the Prediction of Spectral Regrowth for Some RF Amplifiers

The gain compression (am-am), phase distortion (am-pm), and spectral regrowth of an RF amplifier may be found from measurements of the complex modulation envelope. The relationship between the distortion and spectral regrowth is explored by modeling the am-am and am-pm, and then simulating spectral regrowth from the distortion model. Comparison of measurement and model results shows that when hysteresis is present in the amplifier am-am and am-pm distortion, a model with memory is needed to predict the spectral regrowth accurately (within 1 dB).