Application Of The Reconfigurable Technology In The Amplifier

For a long time,the design of the amplifiers has been the focus and hotspot of the RF front-end design.The continuous emergence of new wireless communication standards and the increasing number and variety of communication information also put forward different performance requirements for RF transmitters.With the development of the 5G era,the requirements of bandwidth and efficiency for power amplifier are getting higher and higher.Doherty power amplifiers are widely used in transmitters because of their high back-off efficiency.And the direction of the research has been guided by its demand for bandwidth.Post-matching technology is used to improve Doherty amplifiers'bandwidth,but it often affects the efficiency and power specifications of the power amplifier.Combining the Doherty technology with the reconfigurable technology can not only improve its power and efficiency indicators as much as possible,but also adapt to the needs of different frequency bands in the modern communications field.This article expands the application of the reconfigurable technology in Doherty amplifiers,and summarizes the work as follows.First of all,this article investigates the research background and development direction of reconfigurable and broadband Doherty amplifiers,introduces various important performance indicators of amplifiers.Then on the basic of analyzes the basic theory of Doherty amplifiers and active load modulation technology,a traditional Doherty power amplifier is designed,and be compared with the efficiency of class AB power amplifier.and explained the Doherty power amplifier's ability to improve efficiency at the state of low input power.In order to solve the problem of the narrow bandwidth of the Doherty power amplifier,the third chapter introduces the reasons for limiting the bandwidth of the Doherty power amplifier.On this basis,it proposes a method of replacing the traditional quarter impedance line with post-matching technology to increase the bandwidth.Based on this theory,a Doherty power amplifier working at 1.4GHz-1.8GHz was designed.In this band,1dB gain compression point power is 39.2-40.1dBm,1dB compression point efficiency is 42.3-48.2%,6dB power back-off Point efficiency is 30.1-36.1%,saturated output power is 40.6-41.2dBm,and small signal gain is 9.6-10.8dB.The post-matching technology sacrifices power and efficiency indicators while increasing the power amplifier bandwidth.In order to meet the needs of different frequencies and improve power and efficiency as much as possible,Chapter 4 designs a reconfigurable Doherty power amplifier.This power amplifier can achieve 1.58GHz to1.96GHz frequency switching.At 1.58GHz,the compression point power gain is 10.8dB,P1dB is 40.3dBm,1dB compression point efficiency is 48.3%,6dB back-off point efficiency is 39.9%,P_sat is 41.5 dBm.At 1.96GHz,the power gain at the compression point is 9.1dB,the P1dB is 40.4dBm,the 1dB compression point efficiency is 43.8%,the6dB back-off point efficiency is 30.2%,Psat is 41.0dBm.