Broadband High-efficiency Power Amplifiers And Multiplexing Doherty Synthesis Technology

With the continuous development of the communication field,all applications have higher and higher requirements on transceivers,especially the rapid development of internet industries,which are promoting the communication field constantly to present new technologies and standards.The main research scope of this thesis will focus on power amplifiers(PAs)in the transmission system.Research hot topics of power amplifiers can be summarized as three points: wideband,linearization and high-efficiency.The contents and innovations of this thesis are concluded as follows:1.In this thesis,the traditional high-efficiency PAs and continuous mode PAs will be briefed with comparisons of two design methods from the drain current waveform,voltage waveform and impedance solution space.Meanwhile,a continuous power amplifier operating from 1.7 to 2.7 GHz is designed,and its simulation results show that its in-band power-added-efficiency is over 70% in saturated state,and the maximum efficiency is 76.3%.On the other hand,its saturated output power is between 41.1 dBm and 42.6 dBm,and its saturated power gain is between 14 dB and 15.6 dB with superior flatness.2.In this thesis,in order to challenge second harmonic impedance of continuous power amplifier being strictly constrained by pure reactance,a new design method of constrained sub-optimal impedance area is found to explain that PAs can still achieve high-efficiency performance by using second harmonic impedances without pure reactance.Moreover,a system automatical synthesis method of broadband matching network is proposed at the same time,which can accurately control the range of the fundamental wave and harmonic impedance together.The bandwidth of power amplifiers can be extended,and the performance of the power amplifiers will be improved by utilizing the proposed method.This method can lead the design of ultra-broadband or multi-octave power amplifiers.In addition,a multi-octave PA operating from 0.25 to 1.25 GHz is designed.The measured results show that its saturated output power within the bandwidth is between 40.75 dBm and 42.31 dBm,saturated drain efficiency is from 68.3% to 71.4%,and saturated gain is between 11.89 dB and 14.46 dB.3.After discussions on traditional Doherty power amplifiers,this thesis deals with a modified three-way Doherty power amplifier structure,which can greatly extend the operating bandwidth through switches.Meanwhile,three modes of active load modulation networks are proposed to replace the traditional power combining technology.In addition,an ultra-wideband Doherty power amplifier operating from 1.8 to 3.4 GHz is demonstrated.The measured results show that its saturated output power operating from 1.8 to 2.7 GHz is between 42.6 and 43.9 dBm.The drain efficiency at saturated state is from 52.5% to 67.8%,and it is from 42.1% to 45.3% at 6 dB output power back off.When the output power is at a low level,its power gain is around 12 dB,and when the power amplifier is saturated,the gain falls between 8.1 dB and 9.1 dB.In addition,in the bandwidth of 2.7 to 3.4 GHz,its saturated output power is from 42.6 dBm to 43.7 dBm,the saturated drain efficiency is between 52.1% and 65.3%.The drain efficiency at 6 dB output power back off is between 40.4% and 44.7%.When the output power is at a low level,the power gain is around 13 dB,and the gain is between 9 dB and 10 dB when the amplifier is saturated.4.After discussions with reconfigurable power amplifiers,the advantages and limitations of reconfigurable power amplifiers will be analyzed.Meanwhile,a novel reconfigurable structure of Doherty power amplifier utilizing switch control networks is proposed.The bandwidth expansion is achieved by converting the frequency band through switches.A reconfigurable Doherty power amplifier working from 1.8 to 3.4 GHz is demonstrated,and the measured results show that its saturated output power operating from 1.8 to 2.7 GHz is between 42.8 and 43.9 dBm,its drain efficiency at saturation state is from 45% to 63.5%,and it is from 37.8% to 50.2% at 6 dB output power back off.When the output power is at a low level,the power gain is from 8 dB to 13 dB,and when the power amplifier is saturated,the gain is between 7.6 dB and 10.3 dB.In addition,in the bandwidth from 2.7 to 3.4 GHz,its saturated output power is from 42 to 43.7 dBm,the saturated drain efficiency is between 52.2% and 60%.The drain efficiency at 6 dB output power back off is between 37.3% and 43.2%.When the output power is at a low level,its power gain is around 11 dB,and the saturated gain is between 7 dB and 9 dB.