Study On The X-Parameter Extraction And Simulation Of RF Power Amplifiers Based On NVNA Measurements

The rapid development of wireless communication requires higher performance of RF power amplifiers. RF power amplifiers should provide higher power and efficiency, and should be smaller, which means that the RF power amplifiers need to work under nonlinear conditions. However, the distortion resulting from nonlinearity, such as harmonic distortion and inter-modulation distortion, will affect the performance of the entire system. So the electronic engineers badly need a model to describe the distortion of power amplifiers accurately. On the demand of the industry, in 2008 Agilent put forward the X-parameters model with the scientists'and engineers'research. The model can describe the behavioral trait of nonlinear devices, which settled many difficulties in RF field and made the design of the RF engineers easier.This thesis discussed the X-parameters model in detail. Firstly, the measurement instrument was introduced at large, especially the calibration technique. Secondly, the paper derived the X-parameters model and gave an intuitive interpretation. Finally, an RF power amplifier was measured in use of NVNA, and algorithm was put forward to extract the X-parameters from the measurement data, and the model was used to do some simulations so that the correction and accuracy of the model could be validated. What's more, in order to process the measurement data easily and provide a software system for the measurement system developed independently, a software system analyzing the X-parameters was explored in MATLAB, which could preprocess measurement data, model X-parameters and visualize measurement data and X-parameters.It's a difficult work to describe the behavioral trait of nonlinear devices, because the conditions were getting more and more complicated, which made nonlinearity more and more critical. However, X-parameters could only characterize accurately the nonlinear device in weak nonlinearity. With some impulse stimulations, there was not only nonlinearity but memory effects. So much more advanced model was needed to solve the difficult problem.