Linearization of power amplifiers with mismatched output impedance using on-line digital pre-distortion structure

Abstract

This letter introduces a novel on-line digital pre-distortion structure for linearizing RF power amplifier under the output impedance mismatch conditions. Unlike traditional off-line structures, the proposed structure updates its weight parameters adaptively synchronizing with the power amplifier load impedance. Furthermore, this letter analyses with a MOSFET model and proves that the output conductance of MOSFET are relevant to nonlinearity of power amplifier with variable load impedance. To verify this structure and the analysis, a simulation on MATLAB Simulink was built using a N-channel MOSFET based on Shichman-Hodges model. Proposed on-line Digital Pre-Distortion structure significantly acquired better linearity performance with variable load impedance than conventional off-line structures.