Design And Research On The A-Doherty

RF power amplifier is one of the core module of wireless communication system,and also the most energy consuming unit. The efficiency of the system is directlydetermined by that of the RF PA. Signals with high PAR are used by modern wirelesscommunication systems. In order to amplify the signal without distortion, PA works at ahigh back off region, while the efficiency drops dramatically. At present, there are someefficiency-enhancement technologies that can enhance the efficiency in a certain backoff range, among them, Doherty amplifier has been actually applied for its relativelysimple and availability. However, it also has a number of shortcomings, so the industry’sproposed asymmetrical Doherty amplifier.Firstly, this paper introduces the basic theory of RF PA and efficiency enhancementmethods. Secondly, analyzes the basic theory of Doherty amplifier and points out itsshortcomings. Thirdly, decides to adapt the structure of A-Doherty, uses theoreticalformula to analyze the improvements in the performance of A-Doherty, comparing totraditional Doherty, from the view of the adoption of unbalanced splitter and differentamplifier tubes. Finally, uses ADS simulation tool to design and implement anA-Doherty based on the desire of WCDMA RRH project, after a lot of debugging,ultimately achieves the desired design goals. The results show that A-Doherty has asubstantial improvement in efficiency compared with traditional Doherty.Throughout the whole process, my main work:1. Analyze of the basic theory of RF PA and Doherty amplifier.2. Point out the shortcomings of the conventional Doherty amplifier and a numberof improvement methods.3. Use ADS Momentum tool to simulate A-Doherty.4. Design and complement an A-Doherty, after lots of debugging, ultimately achieve the desired goals.5. Analyze the testing results.