The Research And Design Of RF CMOS Envelope Tracking Power Amplifier

As the rapid development of wireless communication technology,Power amplifier is the core module of RF transceiver in wireless communication system,require low cost,low power,high efficiency,and high integration.The complex modulation methods of modern communication systems impose higher and higher requirements on the linearity and efficiency of power amplifiers.Therefore,it is great significance to design a power amplifier with more comprehensive performance such as power consumption,efficiency,and linearity.This paper briefly introduces the research background and significance of the thesis and then summarizes the current situation and development trend of class E RF power amplifier and envelope tracking power amplifier.Finally,based on the theoretical study of RF power amplifier and envelope tracking technology,A power amplifier applied to a wireless local area network(WLAN)and A dual-mode envelope shaping method combined Knee voltage shaping and constant gain shaping applied to envelope tracking system.(1)A high efficiency,high gain,and good output power 2.4GHz class E power amplifier for wireless local area networks(WLAN)is proposed.The amplifier driver stage uses current multiplexing technology to reduce power consumption,increase gain,and ensure that the power stage operates in the on-off state.,the power stage uses transistor stacking technology and capacitive voltage divider technology to reduce transistor voltage stress,reducing the risk of breakdown of transistor devices and improves output power,mid-node impedance tuning technique used to reduce phase distortion of power stage.Design a reasonable impedance matching network to achieve the best power transmission.The simulation results show that under the 1.8V power supply voltage,the power amplifier has a power-added efficiency of 41.3% and a maximum output power of 13.9dBm.At the same time,the power gain is 41 dB.(2)A new envelope shaping optimization method applied to envelope tracking system is proposed.This paper analyzes and compares the traditional envelope shaping methods,the Knee voltage envelope shaping method is proposed to compensate the voltage in the low voltage region to solve the problem of poor linearity in the low power output of the conventional envelope shaping method,and to optimize the linearity.The Knee voltage envelope shaping method and the constant gain envelope shaping method are combined to implement a dual-mode envelope shaping method to optimize the linearity and efficiency of the entire envelope tracking system.The simulation results show that compared to traditional fixed-voltage power amplifiers,this method improved power amplifier efficiency.Compared with the traditional envelope shaping method,the system has less than 4% EVM in the low output power area,and less than 3% EVM in the high output power area,realizes the optimization of the linearity of the envelope tracking amplifier system.The circuit design of this paper is implemented in 0.13μm CMOS process.Co-simulation and optimization design are performed using Cadence and ADS.