| The steady development of modern wireless communication technology and the high requirements for the performance of the RF system make the RF power amplifier gradually work in the nonlinear region or even the saturation region.The strong nonlinearity and memory effect of RF power amplifier under the excitation of high-power signal will have an important impact on the performance of communication system.Therefore,accurate and effective circuit simulation design of RF power amplifier model becomes very important.Modeling the power amplifier to accurately describe its nonlinear characteristics had became a hot topic in power amplifier research in recent years.In this paper,based on the X-parameter model theory,the RF power amplifier circuit under large signal excitation is modeled,and the nonlinear characteristics of the power amplifier and its measurement indicators are accurately characterized.The main research contents are summarized as follows:Based on the static X-parameter and dynamic X-parameter modeling theory,combined with the memory effect of load traction and power amplifier,a new X-parameter power amplifier modeling scheme is proposed.A novel feedforward(FF)structure using amplitude,load reflection coefficient and frequency three variables as output signals is used to extract a nonlinear function that characterizes the memory function using a dual memory path model to replace the model kernel function,while using a step signal instead of the original two-tone signal extraction model to simplify the model's extraction scheme.Through simulation testing,the new modeling scheme can be used to describe RF power amplifiers with nonlinear memory effects more quickly and accurately.Used the Volterra series behavior model to combined with the X parameter behavior model effectively.The modeling scheme using Volterra series kernel instead of the traditional X-parameter model kernel function is proposed.The Vandermonde determinant is used for theoretical derivation,and the scheme is used to accurately model the power amplifier.This method breaks the limitation of the traditional single behavior model to describe the nonlinear characteristics of the power amplifier,and improves the model representation accuracy and the application range of the model.It can be verified by simulation that the model can be more accurate and effective for the RF signal excited by the two-tone signal than the traditional X-parameter behavior model.The nonlinear behavior of the power amplifier is predicted.Modeling the power amplifier based on the X-parameter model can obtain accurate results close to the actual characteristics of the power amplifier.This paper aims to characterize the memory effect of the power amplifier under the harmonic mismatch condition and predict thepower amplifier under the multi-tone signal excitation condition.In the case of characteristics,the corresponding modeling scheme is proposed respectively,so that the X-parameter has higher universality in the modeling process of the power amplifier,and can provide an accurate reference in the power amplifier design process,thereby shortening the power amplifier development cycle.The paper has 36 figures,3 tables,and 68 references. |
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