【作者】 李鹏；

【导师】 陈鹏；

【作者基本信息】 大连海事大学 ， 信息与通信工程， 2022， 硕士

【摘要】 随着无线通信业务的快速扩展,数据传输速率显著提升,有限的频谱资源已经很难满足高速无线通信的需求。对全双工关键技术的研究,可以有效缓解当今无线频谱资源紧缺的难题,同时实现在有限的频段内进行高速数据传输。将全双工技术应用于WLAN中,能够提高WLAN的传输速率、传输距离和可靠性。环行器、带通滤波器和功率放大器是全双工射频前端的重要器件,本文主要对应用于WLAN全双工射频前端中的环行器部分、带通滤波器和功率放大器进行研究,论文完成的工作主要包括:(1)设计了两种工作在WLAN的高隔离收发双工器结构,一种为环行器、功率分配器和巴伦的组合;另一种为定向耦合器和环行器的组合。两种组合结构均是通过幅度和相位对消技术提高隔离度。设计了威尔金森功分器和宽带平面巴伦,利用功分器、巴伦和环行器设计基于巴伦的收发双工器结构,实测整体结构在2.02～2.79GHz频带内的隔离度值大于40dB,在2.42～2.68GHz频带内的隔离度值大于50dB,在2.51GHz时,最大隔离度值为60.7dB。随后设计了三分支线微带耦合器,采用缺陷地结构并在端口处加载二分之一波长并联开路支节,减小加工难度和拓展工作带宽。利用耦合器和环行器设计基于定向耦合器的收发双工器结构,实测整体结构在2.25～3.1GHz频带内的隔离度值大于25dB,在2.6GHz时,最大隔离度值为47dB。与仿真结果相比,测量结果具有一定的频率偏移和较大的插入损耗。(2)考虑到高隔离收发双工器结构实测结果与仿真结果存在偏差,设计了一款基于混合环的电路拓扑结构。基于混合环180°的相位特性,通过幅度和相位对消技术提高整体结构的隔离度。设计了一款混合环,用双面平行带线代替微带线,引入双面平行带线反相单元代替λ/2传输线,减小了混合环尺寸。在此基础上,用一条高阻抗线并联谐振枝节代替传统的λ/4传输线,实现混合环尺寸的进一步缩小,并能够抑制高次谐波。利用混合环和三个功分器设计组合结构,实测结果表明在1.5～3.5GHz频带内的隔离度值均大于35dB,在中心频率2.4GHz处的隔离度值大于50dB,展现出很好的隔离性能,实现保护收发系统的作用。(3)设计了一款带通滤波器和一款功率放大器。使用加载阶梯式阻抗谐振器的微带传输线和Hilbert分形缺陷地结构单元设计带通滤波器,实测结果表明滤波器的阻带得到了抑制,过渡带更加陡峭,中心频率2.4GHz处插入损耗为1.71dB,相对带宽为10.8%,滤波器的回波损耗值在通带内大于10dB。基于Ga N晶体管NPTB00004A设计2.4GHz功率放大器,实测结果表明最大输出功率为35.81dBm,PAE为46.89%。(4)对全双工射频前端系统进行测试,结果表明全双工射频前端系统实现了良好的隔离度值和稳定的功率输出。更多还原

【Abstract】 With the rapid expansion of wireless communication services,the data transmission rate has significantly increased,and the limited spectrum resources have been difficult to meet the needs of high-speed wireless communication.The research on the key technology of full duplex can effectively alleviate the problem of shortage of wireless spectrum resources,and realize high-speed data transmission in a limited frequency band.Applying full-duplex technology to A WLAN improves the transmission rate,transmission distance,and reliability.Circulator,bandpass filter and power amplifier are important devices in the full-duplex RF front end.This thesis mainly studies the circulator,bandpass filter and power amplifier in the full-duplex RF front end of WLAN.The work completed in this thesis mainly includes:(1)Design two kinds of high isolation transceiver duplexer structure working in WLAN,one is the combination of circulator,power distributor andBarron;The other is a combination of directional coupler and circulator.The isolation degree is improved by amplitude and phase cancellation.Wilkinson power splitter and wideband planar Barron are designed.The structure of transceiver duplexer based on Barron is designed by power splitter,Barron and circulator.The measured isolation value of the whole structure is greater than 40 dB in 2.02～2.79 GHz band,and greater than 50 dB in 2.42～2.68 GHz band.The maximum isolation value is 60.7 dB.Subsequently,a three-branch line microstrip coupler was designed.The Defective Ground Structure(DGS)was adopted and a one-half wavelength parallel open circuit branch was loaded at the port to reduce the machining difficulty and expand the working bandwidth.A transceiver duplexer Structure based on directional coupler was designed using the coupler and circulator.The measured isolation value of the whole structure is greater than 25 dB in 2.25～3.1 GHz frequency band,and the maximum isolation value is 47 dB at 2.6 GHz.Compared with the simulation results,the measured results have certain frequency offset and larger insertion loss.(2)Considering the deviation between the measured results and the simulation results of the high isolation transceiver duplexer structure,a rat-race coupler based circuit topology is designed.Based on the phase characteristics of 180° rat-race coupler,the isolation degree of the whole structure is improved by amplitude and phase cancellation technology.Double-sided Parallel Strip Line(DSPSL)is used to replace microstrip line,and DSPSL inverting unit is used to replace transmission line,thus reducing the size of rat-race coupler.On this basis,a high impedance parallel resonant branch is used to replace the traditional transmission line,which can further reduce the size of the rat-race coupler and suppress the high harmonics.The measured results show that the isolation degree is greater than 35 dB in the 1.5～3.5 GHz frequency band and greater than 50 dB in the center frequency of 2.4 GHz,showing good isolation performance and realizing the protection of the transceiver system.(3)A band-pass filter and a power amplifier are designed.A band-pass filter was designed using a microstrip transmission line loaded with a stepped impedance resonator and a Hilbert fractal DGS element.The measured results show that the stopband of the filter is suppressed,the transition band is steeper,the insertion loss at the center frequency of 2.4 GHz is 1.71 dB,and the relative bandwidth is 10.8%.The return loss of the filter is greater than 10 dB in the passband.The 2.4 GHz power amplifier is designed based on Ga N transistor NPTB00004 A.The measured results show that the maximum output power is 35.81 dBm and the PAE is46.89%.(4)The full duplex RF front-end system is tested.The results show that the full duplex RF front-end system achieves good isolation and stable power output.更多还原