Design Of High Efficiency Dual-band Doherty Power Amplifier

With the rapid development and evolution of 5G communication,the spectrum resources are increasingly scarce,and the frequency bands allocated to operators are fragmented.For the smooth transition and upgrade of wireless communication system,the RF front-end is required to meet the multi frequency or broadband work at this stage.As the most widely used Power Amplifier(PA)technology in today's wireless communication system,Doherty PA needs to meet the efficiency and linearity,and simultaneously develop towards the direction of multi frequency or broadband.In this paper,the high efficiency and dual-band frequency of Doherty PA are analyzed and studied,and the test and verification are completed.The work of this paper is mainly divided into three parts as follows:(1)The dual-band frequency matching network is designed by using Bilateral microstrip branch line,and on the basis,the band notch filter structure is added to increase the isolation between the dual frequency bands.Finally,a dual-band PA working at 1.5GHz and 2.4GHz is obtained.At 1.5GHz and 2.4GHz,the additional power efficiency is 66% and 64.5% respectively,and the gain is 12.8dB and 11.5dB.The transmission power and efficiency at 2GHz are basically 0,and the isolation between the two bands is obviously improved.(2)According to the classic theory of Doherty technology,a Doherty PA with working frequency of 3.4GHz-3.6GHz is designed.In this frequency band,the saturated drain efficiency of Doherty PA is 65%-70%,the saturated output power is above 43 dBm,and the 6dB back drain efficiency is 45%-50%.Through the design and research of the Doherty PA,it lays a foundation for the following dual-band Doherty design theory.(3)Combining the dual-band matching network and the dual-band bias network,the idea of impedance reverse traction is proposed.A dual-band Doherty PA with high isolation and high efficiency is designed,which works at 2.6GH and 3.5GHz.The saturated drain efficiency of the amplifier is 65% and 64% at 2.6GHz and 3.5GHz,the saturated output power is over 43.5dBm,and the 6dB back drain efficiency is 50% and 45% respectively.The design goal of dual-band Doherty PA is basically realized.