Polyharmonic Distortion Characteristics Modeling For Radio Frequency Power Amplifier

Fundamental to the Computer-aid Design for RF Power Amplifier (RFPA) is to build adequate nonlinear large-signal RF models. If these models exist, nonlinear devices design and simulation can save numerous iterations, the devices design becomes easier and simple, to a large extent, the development cycle of the electronic products turns to be curtate. The introduction of the notion of Large-signal Scattering Function for modeling nonlinear RFPA exploits a novel way for the researchers to solve the existence problems for modelling. However, in contrast to traditional scatter parameter, for majority of current-users the concept of Large-signal Scattering Function is not familiar and more challenging. Based on the theory of large-signal scattering function, this dissertation aims to exploit a general model for the Poly Harmonic Distortion characteristics of RFPA.Firstly, this dissertation summarizes the characters of the existed models for RFPA, for example, Physical Level Model, Circuit Level Model and Behavior Level Model and analyses the merits and shortcomings of these models. And then the dissertation systematically introduces the performance criterions of RFPA, including Output Power, Power Efficiency, Harmonic Distortion, Intermodulate Distortion and Band Range etc. With regard to the nonlinear characteristics of RFPA, this dissertation contrastively analyses the time-domain and frequency-domain methods of nonlinear analysis, introduces the fundamental principals of harmonic balance methods and the prerequisites for nonlinear behaviors analysis of RFPA.Secondly, this dissertation proves that, by introducing a third fundamental frequency signal as a reference, the phase of ratios between any two harmonically related complex signals remains a time-invariant, following by correspondingly experimental confirmation. In addition, based on nonlinear large-signal scattering functions theory and Harmonic Superposition Principle, this dissertation presents a novel method to linearize the scattering function in a form that is similar with classical scattering parameter when considering the influence of the conjugated term of incident signal. Moreover, in case of weakly nonlinear device, combining phase normalization and linearization technique, this dissertation analyses the functions of the parts in the expression of linearized scattering function in polar coordinates and predict the characters of the track of reflected waves. Further examination of these characters, this dissertation mathematically validates the origin of conjugated term and illuminates the significance for the existence of conjugated term.Finally, this dissertation emphasizes the extensive application merits of the above Poly Harmonic Distortion characteristics model. Furthermore, to testify the linearization model, based on measurements data, this dissertation applies this linearization model technique and classical scatter parameter method for modeling High Electron Mobility Transistor (HEMT) on Large Signal Network Analyzer platform. After contrasting the linearization model with classical scatter parameter model for the measurements data, this dissertation concludes with the comprehensive application foreground and feasibility of the model for modeling RFPA in near future.