New aspects on nonlinear power amplifier modeling in radio communication system simulations

A new semi-physical behavioral amplifier model to characterize the AM/AM conversion of a bipolar solid-state high power amplifier in a mobile phone is introduced. The functional model is able to copy the low-voltage features of a real amplifier causing crossover distortion. Hence it gives an improved description of the nonlinearity of Class AB amplifiers widely used in mobile phones employing a linear modulation scheme. The AM/AM conversion model is accompanied by an AM/PM conversion model function to complete the amplifier model. The model is utilized in mobile communication system studies to investigate the increase of common channel and adjacent channel interference due to the nonlinear behavior of the amplifier. The new model is compared to the existing widely used functional models, and it is found to give an excellent match to the two-tone performance of a measured amplifier