Behavioral Modeling of Outphasing Amplification Systems

Abstract

This paper presents a comparison of existing and novel behavioral models targeted at the outphasing power amplifier (PA) architecture. A comprehensive comparison of ten modeling strategies is presented in the results. Novel techniques for outphasing PAs, such as vector switched and dual path time series, are also presented for the first time. Investigation of such techniques was driven by the analysis of outphasing operation at minimum output powers, demonstrating the generation of frequency-dependent amplitude and phase deviations, which can be difficult to characterize. The increased robustness was achieved at the cost of additional complexity; for practical implementation, time series coefficient reduction techniques were also evaluated. The results of all modeling approaches are experimentally validated for the wideband operation of an NXP 19-W GaN digital outphasing amplifier module. Considering computational complexity and accuracy for system-level modeling across all presented options, a subset of existing and new models is identified as best suited for modeling outphasing PAs.Index Terms-Behavioral model, outphasing, radio frequency (RF) power amplifier (PA), Volterra.

Behavioural Models for Distributed Arrays of High Performance Doherty Power Amplifiers

“…The application of piecewise Volterra models to high efficiency power amplifiers has been carried out previously [11], [12], [13], [14]. The use of an instantaneous amplitude or power measurement with a bank of Volterra kernels, one for each region over the operating range of the PA.…”

Analysis and Design of Outphasing Transmitter Using Class-E Power Amplifiers With Shunt Capacitances and Shunt Filters

“…This load modulation can significantly improve the average efficiency of the transmitter. However, since these combiners introduce significant nonlinear distortion, digital predistortion techniques (DPD) are often required for these transmitters [26]- [28]. Partially isolated combiners provide a trade-off between nonlinear distortion and linearity and are capable of improving the bandwidth performance of an outphasing transmitter [24].…”