Behavioral model on transmitter power amplifier and IQ imbalance

Abstract

This thesis is dedicated to the subject of the behavioral model of two most important analog impairments in modern wireless transmittersin-phase/quadrature (IQ) imbalance distortion and power amplifier (PA) nonlinear memory distortion. Despite their distinct physical characteristics, and unlike conventional ways of treating them differently and separately, this thesis is to treat these two seemingly different distortions equally and model them uniformly. Specifically, the main research efforts have gone through the following two stages: In the first stage, these two distortions are treated equally while independently, and compensated using the same methodologydigital predistortion. In this stage, the main objective is to find a better behavioral model for each distortion. Then in the next stage, these two distortions are merged as one black box, and characterized by a single behavioral model. The objective of this stage is to unify the view of the two distortions, abstract it in the implementation, and save the resources by unifying and simplifying the model. After the introduction chapter, the background of the two analog distortionstransmitter (TX) in-phase/quadrature imbalance and power amplifierare presented, followed by the general discussion of system-level simulation and digital predistortion, where the quality of the behavioral model determines both performances. Then a comprehensive literature review is engaged on the subjects of transmitter in-phase/quadrature Imbalance and power amplifier, from where it is clear that the current available behavioral models cannot satisfy the demanding requirements, and hence efforts are necessary to find a better, simpler, more accurate, while free-of-side-effects model.