| In order to achieve mass data transmission and improve the data transmission rate,the new generation of wireless communication systems generally use more complex modulation technology to improve spectrum efficiency,resulting in a high PAPR.For the peak-to-average signal,the power amplifier,which is the core component of the base station system,must work in the back-off state to improve the linearity,which will lead to the decrease of efficiency.Efficiency is an important indicator of the power amplifier.In view of this situation,the base station system usually adopts the power amplifier with Doherty structure to ensure the efficiency of the power amplifier in the state of fallback.Under this background,this thesis mainly studies how to apply high efficiency harmonic amplifier to Doherty power amplifier structure to improve the efficiency of Doherty power amplifier.The main work is summarized as follows:Based on the characteristics of class F power amplifier,this thesis studies and analyzes how to apply class F power amplifier to Doherty structure.The impedance of the current end face of the main power amplifier and the impedance of each branch at the load junction under different input modes of class F power amplifier are analyzed in detail.Based on theoretical analysis,a narrow-band and high-efficiency F-class Doherty power amplifier is designed.It is verified that using harmonic power amplifier as the main power amplifier unit in Doherty power amplifier structure can further improve the return efficiency of Doherty power amplifier.After the simulation and measure,the leakage efficiency of the F class Doherty power amplifier is up to 60% when the saturation output power is 44 dB.In order to expand the bandwidth of high efficiency Doherty power amplifier,the hybrid power amplifier with broadband and high efficiency is used as the main power amplifier unit.According to the impedance characteristics of hybrid continuous class,how to make Doherty power amplifier work in hybrid continuous class is analyzed and studied.Based on the theory of S parameter matrix and broadband matching network,the design method of broadband inverter network is introduced.Based on the structure of Doherty power amplifier,a broadband and high efficiency Doherty power amplifier based on hybrid continuous mode is designed.The measured results show that the drain efficiency is higher than 50% when the saturation output power returns 6dB,which proves the feasibility and superiority of Doherty power amplifier based on hybrid continuous modes. |
PDF Full Text Request