Study Of High Efficiency RF Power Amplifier

RF power amplifier is one of the most important parts in wireless communication system, until today in development of RF power amplifier from the middle of the20th century, the kinds and forms are increasing, and the application fields are also growing. In recent years, in order to meet the requirements of the wireless communication system, RF power amplifier has to achieve light weight, small volume and low power consumption, etc. So it is imperative to research on improving the efficiency of power amplifier, high efficiency study of RF power amplifier has received the widespread attention. Traditional power amplifiers (containing class-A, class-B, class-AB, and class-C) by adjusting the working state (i.e., reduce the transistor conduction Angle) to improve the efficiency, Under the traditional working condition the power amplifier’s voltage and current exist at the same time, in order to reduce the power consumption of a transistor to zero, then the output power is also reduced to zero, As a result, the way by reducing conduction Angle to improve the power amplifier’s efficiency had reached a bottleneck. So the new type of RF power amplifier arises at the historic moment, which working under switch type, and alternating voltage and current conduction (containing class-D, class-E and class-F). Its biggest extent reduce the overlap degree of voltage and current, so as to reduce the power consumption of the power transistor itself, and in theory the transistor itself power consumption can be reduced to zero, the efficiency of the RF power amplifier can reach100%theoretically. For class-D power amplifier of double tube push-pull form, above MHz band, due to the switch delay effect transistor itself, the voltage and current of serious overlap, lead to serious decline in efficiency. However, the use of class-E RF power amplifier of the single tube amplifier overcomes the shortcomings, is suitable for the higher frequencies, the efficiency can achieve more ideal at the same time. So on the study of high-efficiency class-E RF power amplifier has the vital significance.Firstly, this paper introduces the basic concept of RF power amplifier, development course, led to a practical significance for research in the high-efficiency RF power amplifier; Secondly, this paper briefly introduces the several types of the traditional radio frequency power amplifier and several new switch type of RF power amplifier; Once again, choose E class working patterns, based on the M/A COM’s MRF166C models of power transistor,the high-efficiency141MHZ RF power amplifier with structure of the shunt capacitance has been designed, Through the theoretical calculation and the RF circuit simulation software, the high efficiency RF power amplifier’s circuit was obtained, the amplifier achieves a drain efficiency of78.2%,20.8W output power when operated from a driving power of1W and28V supply voltage; Finally, the object of high-efficiency RF power amplifier has been created, the physical efficiency and harmonic parameters has been tested too, the amplifier achieves a drain efficiency of72.5%and PAE of69.3%,22.2W output power when operated from a driving power of1W and28V supply voltage, and compared with theoretical calculation value, after analysis, the measured results and the theoretical calculation results of fitting, not only sufficient to demonstrate the validity of this design, but also for the class E RF power amplifier efficiency research provides a more valuable reference.