The Research Of Hybrid Envelope Tracking Power Modulation Technology

With the continuous development and evolution of wireless communication technologies,data transmission rates and spectrum utilization rates are rapidly increasing.This should be attributed to the increasingly complex high-order modulation schemes employed in wireless communication systems,but at the same time,which leads to high peak-to-average ratio(PAPR).In order to ensure the linearity of the system,the power amplifier usually needs to be operated in an extremely high back-off power region,which results in a sharp drop in efficiency.Envelope tracking technology,as a dynamic power modulation technology,can effectively improve the efficiency of the power amplifier in a high back-off state.Bandwidth,efficiency,and linearity are the limiting factors of current power modulators,and they are also the focus and difficulty of research.In order to obtain good comprehensive performance,the hybrid power modulator is deeply studied in this paper.The main research contents are as follows:1.In this thesis,Firstly,based on the basic structure and implementation principle of envelope tracking power amplifier,the essential structure of various power modulators is analyzed and summarized.Then,the key factors that limit the performance improvement are analyzed.Finally,based on the current research progress,a potential solution to improve the overall performance of the power modulator is proposed,which provides a feasible reference for the design of specific parameters.2.In this thesis,the design method of series and parallel hybrid power modulators is systematically studied.Based on this,the switch-linear hybrid power modulator based on multilevel series-parallel architecture is deeply studied.Combined with the time domain and frequency domain characteristics of the envelope signal and the loss model of each part of the power modulator,a method for optimal design of the system is proposed.Based upon the proposed design method,the power modulator can achieve better overall performance,and its bandwidth and efficiency are significantly improved under the premise of ensuring linearity.Using this optimization theory,the hybrid power modulator designed in this paper can track LTE signals with a bandwidth of 10 MHz.The experimental results show that the average efficiency of 83.04% is realized with the output peak power and average power of 67.6W and 26.97 W,respectively,while the NMSE(normalized root mean square error)of 1.08% is achieved.3.In this thesis,the circuit structure and control scheme of series-parallel hybrid power supply modulator based on switched capacitor architecture are described systematically.At the same time,the design methods of each stage circuit are deeply analyzed.Based on the loss model of each element of the circuit,the overall optimization design method of the system is proposed.The power modulator of the switched capacitor architecture does not include any magnetic inductive components,which facilitates integration.The article focuses on the detailed analysis of the implementation principle and optimization method of the switched capacitor stage.Based on the proposed system optimization approach,a hybrid power modulator capable of tracking LTE signals with 10 MHz bandwidth is designed.The experimental results show that the average efficiency of 74.1% is realized with the output peak power and average power of 32.4W and 11.78 W,respectively,while the NMSE of 1.25% is achieved.