Study Of The High Efficiency Power Amplifier

In the past20years, mobile data services grew rapidly with the development of thecommunications industry, but it presented a huge challenge for the wirelesscommunication technology. It was studied that the annual growth of the demand formobile data traffic is about131%, but the mobile bandwidth is only about55%. In orderto reduce or even to bridge the gap between the twos, LTE-Advanced is developed.With greater bandwidth and higher signal PAPR compared to the2G and3G system,LTE-Advanced makes the RF power amplifier have a higher efficiency, linearity and awider bandwidth.With the feature of simple structure, low cost and significantly improved efficiencyin the fallback, Doherty can also improve the overall linearity combined with thepredistortion technique. So it is considered that Doherty is one of the most promisingtechnologies to improve the RF power amplifier.The thesis uses3.4~3.6GHz hith-efficiency power amplifier as the research object.It expounds the classic Doherty power amplifier circuit structure, theoretical analysis,and gives a variety improved designs of Doherty. According to project requirements, ituses ADS to simulate, optimize and Altium Designer to design PCB based on the basicstructure of the asymmetric Doherty with Cree’s CGH35060F transistor. At last,troubleshooting and test are done.After PAPR suppression, using the LTE-A as a test signal, whose center frequencyis3.5GHz and bandwidth is200MHz, the PAR is6.5dB, average output power is41.3dBm with the average input power14.3dBm, and efficiency is over42%. Withoutthe digital predistortion, ACLR is-20dBc. With the digital predistortion, ACLR is-45dBc. So the design achieves the LTE-A testing requirements.