Multi-fit Power Amplifier Design And Implementation

China is entered into the 3G era accompanying with all three major communication operators running 3G businesses. In technique level, the main advantage of 3G comparing with 2G is the improved speed of WiFi, which results in a higher PAPR that requires power amplifier has a much better linear performance.However, due to the high PAPR of the 3G signals, the PA is working at a very deep backoff situation, which reduced the efficiency greatly. Moreover, PA plays a very important role in efficiency of the wireless station, if considering its'widely application the station. Therefore, improving the efficiency of PA becomes a big issue at present.PA with high efficiency and linearization is the trend in modern communication technique. Among various techniques of efficiency improving, Doherty method is widely accepted by the main society owing to its simple structure, low cost, as well as excellent performance. In addition, Doherty combined with Digital Predistortion (DPD) also has a huge prospect in applications.In the dissertation, current research achievements in PA with high efficiency and linearization are reviewed; Classification and technical parameters of different PAs are illustrated; Circuit structure, working mode, efficiency calculation, as well as modified circuit of Doherty PA are analyzed; Design, construction, and simulation analyzing are conducted by means of ADS software; Last but not least, hardware realization and performance evaluation indicate the modified Doherty circuit is satisfied.Backflow and asynchronous saturated output of the two-channel AP are two problems encountered during detailed simulation investigation. The two problems are solved by employing delaying circuit and asymmetric Doherty, respectively. The modified Doherty is finally passed the test and improved the efficiency.