Study And Implemention Of A New Modified High-efficency Broadband Doherty Power Amplifier

Modern wireless communication systems achieve high data throughput and network capacity on RF signal transmission utilizing an ever-increased number of frequency bands.This requires a high-efficiency power amplifier working in a wide frequency band.This thesis's aimed at realizing a high-efficient broadband Doherty power amplifier with large back-off range,and the major contribution includes:1)Based on the analysis of traditional Doherty power amplifier,a new asymmetric Doherty structure is designed to make a good compromise between the efficiency,linearity,bandwidth and reliability.The design and measurement of the asymmetric DPA based on modify of multi-way Doherty theory.2)A new structure using low-pass bias network to design high-efficiency broadband power amplifier is presented in this paper.Compared with other bias networks,the proposed low-pass bias network shows smaller baseband impedance,which can reduce the electrical memory effect,While it provides a larger radio frequency(RF)impedance,which can prevent the leakage of the output power from bias network.3)Design and implement a Doherty power amplifier?The measured drain efficiency of 55-66%over 700 MHz at 6-8 dB output power backoff and 35-45%at lOdB output power backoff is achieved.CW-signal measurement at 2.4 GHz exhibits a drain efficiency of 55%,50%and 41%at 6 dB,8 dB and 10 dB output power backoff,respectively.With the same average power of 35.5 dBm for the 20MHz modulated signal at 2.65GHz,the ACPR of BPA with low-pass bias network could be linearized to-51 dBc.The proposed broadband Doherty power amplifier is proved to be well-performed and have promising application prospects.To be specific,the discussion of broadband high-efficient power amplifier with large back-off range is beneficial and conductive for the later Doherty power amplifiers' design.