Design And Implementation Of Freouency Reconfigurable Power Amplifier

With the rapid development of radio technology and network technology,the requirement of communication ability is higher and higher.The communication system presents the development trend of multi-band,multi-mode and adaptive.As one of the core devices of RF front-end,power amplifier urgently needs to adapt to this change.In recent years,frequency reconfigurable technology has become a research hotspot for its flexible circuit design and reliable operation in multi-band and multi-mode applications.Under this application background,this paper designs two kinds of frequency reconfigurable power amplifiers.By introducing RF switch and changing the parameters of matching network,they can match to the optimal impedance at different frequencies,so as to realize the multi-band operation of power amplifier,and improve the performance of power amplifier in multi-band operation by using harmonic control and internal matching technology.The main work and innovation of this paper are as follows:(1)Combining frequency reconfigurable technology,harmonic control technology and internal matching technology,an internal matching frequency reconfigurable power amplifier with 3.4-3.6GHz and 4.8-5.0GHz operating frequency band is designed.By controlling the second harmonics of the two operating frequency bands and changing the fundamental matching network by using the turn-on and turn-off of the RF switch,a good matching is achieved in the two frequency bands.At the same time,considering that the parasitic effect of packaged power transistor in traditional power amplifier design increases significantly with the increase of frequency,which leads to the deterioration of high frequency performance of power amplifier.In this paper,the power transistor chip is used to replace the packaged power transistor,that is,the internal matching method is used to design the frequency reconfigurable power amplifier working in two 5G bands.The simulation results show that the drain efficiency of the power amplifier is higher than 70%at 3.4-3.6GHz and 65%at 4.7-5.0GHz,which shows good frequency reconfiguration performance.The test results show that the bandwidth expands to low frequency,the drain efficiency of 3.0-3.6GHz is more than 62%,the saturated output power is between 41.2-42.2dBm,and the gain is 7-9.5dB;The drain efficiency of 4.5-5.0GHz is more than 52%,the maximum saturated output power is 41.3dBm,and the gain is 6.8-8.5dB.(2)A frequency reconfigurable Doherty power amplifier is designed by using frequency reconfigurable matching network and broadband load modulation network with second harmonic matching ability.By adding RF switches into the input matching network of the main and auxiliary power amplifiers,the good matching of the corresponding modules in the reconfigurable frequency band can be achieved.More importantly,the second harmonic of the reconfigurable frequency band can be controlled at the output of the main power amplifier,and making the whole system including the equivalent parasitic parameters of the power transistor,the second harmonic matching network and the output matching network presents the broadband modulation characteristics for fundamental load.It not only meets the impedance requirements of Doherty amplifier load modulation in two frequency bands,but also improves the performance of Doherty amplifier in reconfigurable frequency band.The simulation results show that the Doherty power amplifier based on this method has excellent performance in both frequency bands,and its saturated output power is more than 44.5dBm,the 6dB output back-off and saturated drain efficiency are more than 58%and 70%respectively.The measured results show that the two operating bands are shifted to low frequency,but the two shifted bands show good Doherty amplifier characteristics,which verifies the correctness of the frequency reconfigurable Doherty amplifier design method.The measured results show that the two operating bands are shifted to low frequency,the saturation output power is about 44dBm at 2.3-2.55GHz,and drain efficiency of the 6dB output back off is between 50%-58%,and the saturation drain efficiency is about 60%.The measured saturation output power is more than 43.5dBm at 3.2-3.4GHz,the drain efficiency of 6dB output back off is more than 45%,and the saturation drain efficiency is close to 70%.It can be seen that the Doherty amplifier has good performance in both bands.The correctness of the design method of frequency reconfigurable Doherty power amplifier is proved.