| Power amplifier is an important communication module widely used in front-end transmission devices of various communication networks.However,with the continuous progress of various complex modulation technologies,the peak to average ratio of the signal becomes larger,making it difficult for the power amplifier to maintain an efficient state under power backoff.Therefore,this thesis aims to design a high gain and high efficiency power amplifier module based on the characteristics of peak to average ratio signals in dedicated communication networks.The power amplifier module is composed of four modules: power supply,low noise amplifier,front-end driver amplifier,and final power amplifier.By designing reasonable power amplifier modules,the reliability and performance of communication networks can be improved.Here is a summary of the main research content and innovative points of this thesis:1.The front-end driver amplifier is an important component in the power amplifier module,which amplifies the signal and drives the final stage power amplifier.To solve the problem of non convergence in harmonic simulation when using ADS for power amplifier design,an automated power amplifier design system was adopted for the front stage drive amplifier design.Finally,a front-end driver operating at 1.35-1.8 GHz was designed.The experimental results showed that the output power of the backoff point was25.4-26.8 d Bm,and the gain in the entire frequency band was 15.94-19.47 d B.After digital pre distortion processing,the front stage drive amplifier meets the communication requirements.2.This thesis analyzes the Active load modulation theory of traditional symmetrical Doherty power amplifier.In order to solve the bandwidth limitation of one quarter wavelength line and increase the amount of backoff,this thesis adopts the asymmetric Doherty power amplifier architecture based on post matching network.Finally,a 1.35-1.8GHz final stage power amplifier was designed and tested.The test results show that the drain efficiency of the amplifier is 43.4-50.8% and the saturated drain efficiency is54.5-66.9% when the output is 43.49-45.03 d Bm at saturation,with a backoff of 8 d B.After digital pre distortion processing,the power amplifier meets the communication requirements.3.Finally,a comprehensive test was conducted on the power amplifier module.The test results show that the gain range of the module in the entire frequency band is 42.3-46.98 d B,and the overall efficiency of the module is 27.61-35.55% when backtracking 8d B.The results indicate that our power amplifier module has high efficiency and high gain characteristics,which can meet the challenges brought by complex modulation techniques and improve the reliability and performance of communication networks.4.In order to further reduce the area of the power amplifier module and improve the linearity of the module,this thesis uses the Ga As HBT process to produce a miniaturized front-end driver amplifier chip,which is used to replace the low noise amplifier and frontend driver amplifier in the power amplifier module.Adopting a base adaptive current source bias circuit to reduce the impact of temperature on HBT devices and improve amplifier linearity.Finally,this thesis successfully designed a miniaturized front stage drive amplifier with a frequency range of 1.35-1.8 GHz,and conducted simulation testing.The simulation results show that the minimum output power of the front stage drive amplifier is 35.2 d Bm,the gain fluctuation is 1.5 d B,the maximum AM-AM is 0.74 d B,the maximum AM-PM is 2.02 degrees,and the maximum IMD3 is-44.627 d Bc.These results indicate that the power amplifier chip can effectively reduce the area of dedicated communication network power amplifier modules and improve module linearity,which has important engineering practical value. |
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