High-efficiency Rf Power Amplifier

PA (Power Amplifier) is widely used in the field of Radio Frequency Communication, Wireless/ Cable TV broadcasting and Radar. In order to meet the requirement for the modern PA, the research and design of a high efficient RF PA has become the hotspot of RF frond end.In this paper, based on the design of a PA working with the frequency of 340MHz, output power of 36dBm, completed the research and design of RF PA, and mainly focusing on how to improve the efficiency of RF PA.In the traditional way of designing PA, it is generally accepted that decreasing the operating angle of transistor could improve the efficiency. In case of high requirement of output power, the traditional way could not go any further. The introduction of switch-mode power amplifier has become a novel way of improving efficiency. It decreases the power consumption and also improves the efficiency of transistor by changing the output currency, voltage waveform of transistor. E-type PA is the most typical one.In theory, by the way of driving it, the E-type PA lets the transistor working the switch mode. Through the specific output network, it makes the output current and voltage appear asynchronously, ensuring the on/off Zero Voltage Switch (ZVS), Zero Voltage Difference Switch(ZVDS) to make the theoretical efficiency of 100%. Lots of attention has been drawn to the E-type PA because of the simplicity of the structure. The parasitic capacitor of transistor, matching network, biasing circuit and duty cycle are the key factors to the performance of PA. Based on the analysis above, this paper has done a great deal of research and discussion of the E-type PA in detail. In the last part of this paper, according to an example of designing the E-type PA, we will verify the theoretical analysis, and summarize the design method in practice.In the future, the research of PA will focus on combining the E-type PA with Doherty, EER and LINC structure.