Investigation Of Broadband High-Efficiency Power Amplifier Based On The Load And Supply Modulation

With the increasing demand for wireless transmitting rate and quality,modern wireless communication systems are developing rapidly towards 5^thgeneration.On the one hand,the transmitted modulated signals have wider bandwidths and higher peak-to-average power ra-tios?PAPRs?,so as to improve data rate and spectrum utilization.On the other hand,with the allocations of more and more communication standards,the working frequency spaces of com-munication systems are becoming bigger.Power amplifiers?PAs?,regarded as one of the most important cells in the wireless transmitters,are facing many challenges such as bandwidth,effi-ciency and linearity.The dissertation focuses on the research and development of the Doherty PA?DPA?and dynamic supplied PA to further broaden the bandwidth and improve the back-off?BO?efficiency of the PAs.The major innovation achievements are listed as follows:1.A novel dual-transformation simplified real frequency technique is proposed to synthe-size a broadband Doherty PA operated in 2.2-3.7 GHz.Generalized driving point functions and a united error function are adopted to realize this method.The proposed method can realize the co-design of the carrier and peaking output matching networks to achieve dual-impedance transformation at BO and saturation simultaneously.Compared with conventional designs,no initial guess is required and additional compensating lines are eliminated to improve the per-formance of the DPA.The measurement results show that the designed DPA has a 6-dB BO efficiency of 45%-53%and a saturated output power of 43-44.6 dBm over 1.5 GHz bandwidth.An 80-MHz long-term evolution-advanced?LTE-A?signal is employed to validate the DPA.The DPA can achieve an average efficiency of 46.7%with the adjacent channel leakage ratio?ACLR?levels better than-51 dBc by utilizing digital predistortion.The researches of this part have been published in IEEE Access.2.A concurrent dual-band?C-DB?DPA is proposed to enhance the bandwidth in each fre-quency band.The relationship between the phases of carrier and peaking impedance inverting networks?IINs?and the bandwidth of the C-DB DPA is analyzed for the first time.By designing the carrier and peaking IINs with appropriate minimum phase delays,the bandwidth of C-DB DPA can be enhanced and balanced in both frequency bands.Based on postmatching technique,load impedance at the combining point is optimized by comparing the DPA's bandwidth at BO and saturation.A high-efficiency C-DB DPA is designed and measured at 2.0-2.4 and 3.2-3.6GHz?400 MHz bandwidth each?.The DPA has a 6 dB BO efficiency of 52%-57%and a satu-rated efficiency with the saturated output power more than 44 dBm.The researches of this part have been published in Int.J.RF&Microw.Comput.Aided Eng..3.A high-efficiency envelope tracking?ET?PA is proposed in this part.Firstly,a ET sup-ply modulator is designed with the digitally-controlled series form switch-linear hybrid struc-ture.The efficiency of the supply modulator is improved by optimizing the output levels of multilevel convertors.Then a 1.3-2.3 GHz broadband continuous class-F PA is designed by em-ploying appropriate quarter wavelength bias network to accommodate the frequency response of the supply modulator.At last,a high-efficiency ET PA is constructed by the radio frequency?RF?PA and the modulator.Stimulated by a 10-MHz LTE signal with 8.5 dB PAPR,the ET PA can achieve an average efficiency of 41.7%with the ACLR better than-46 dBc.Compared with the constant supply PA,the average efficiency of the ET PA improves 14.5%.The designs of this part have been published in 2015 Asia-Pacific Micro.Conf.?APMC?and part of the researches have been co-authored in IEEE Trans.Microw.Theory Tech..4.In this part,a broadband supply modulated?SM?PA is designed and constructed by em-ploying a discrete four-level fully-analog SM supply modulator and a 60 W broadband RF PA.A real voltage offset controlled envelope shaping function and a minimum pulse reservation-based switching frequency reduction method are proposed to optimize the performance of the SM PA.The measurement results show that the peak switching frequency of the modulator can decrease four times by the proposed methods.Meanwhile,the SM PA can attain an average efficiency of 40.5%excited by a 40-MHz LTA-A signal with 8 dB PAPR.The researches of this part have been published in Electron.Lett.and 2018 IEEE Int.Wireless Symp.?IWS?.5.An output power reconfigurable and a BO region reconfigurable DPAs are proposed in this part.By combining a harmonic-controlled DPA with two-level supply modulators,the output power reconfigurable DPA can maintain high efficiency at two output power levels,especially the efficiency at lower level improves 8.1%.For the second design,the DPA can be configurable at 6-dB BO and 9-dB BO by adopting RF MEMS switch to change the phase of peaking output matching networks.The designs of this part have been published in 2017 32nd Gen.Assem.Sci.Symp.Int.Union Radio Sci.?URSI GASS?and part of the researches have been co-authored in Wireless Commun.&Mobile Comput.