Combined memory polynomial model for Doherty power amplifiers with memory effects

Abstract

This paper presents a combined memory polynomial model for Doherty power amplifiers with memory effects. The model combines the memory polynomial model with an envelope memory term. Levenberg-Marquardt Method is applied to estimate the model parameters. The model has been successfully validated with 20MHz LTE signals in the test bench, in which the input and output signals of a Doherty power amplifier are sampled by a vector signal analyzer (VSA). Good modeling accuracy can be achieved with normalized mean square errors (NMSE) of about -40 dB by comparison between measurements and modeling results in frequency domain.