Research On Dual-frequency Balanced Power Amplifier At S/C Band

With the continuous development of wireless communication technology,high-performance RF microwave devices have been paid great attentions.As a key component in a transmitter,the bandwidth,output power,efficiency and linearity of a power amplifier play critical roles in communication systems.In recent years,communication systems operate in different communication standards and different frequency bands,where transmitters require sufficient power to feed antenna.Several power amplifiers operated simultaneously not only result in high power consumption,but also increase the cost.Therefore,it is of great significance to study power amplifiers integrated at different frequency bands.Meanwhile,with the advance of GaN semiconductor technology,design of GaN HEMT based power amplifier has become a hot topic.This thesis first introduces the history and latest development about the efficiency and linearization techniques as well as the multiple frequency technology of power amplifiers.Then we introduce the basic performance parameters of the power amplifier,and analyze the balanced amplifier theoretically.The key components for dual-frequency balanced power amplifier,for instance,dual-band power amplifier,dual-band branch line coupler,dual-band 45° phase shift power splitter,are respectively discussed.Finally,the 2.4 and 5.2GHz balanced power amplifier,by integrating the above components,are developed.Both full-wave simulations and measurements are presented.Contributions of this work include(1).A dual-frequency broadband power splitter with 45? phase shifts is studied in depth.The architecture is based on the ?-type network to realize the flat phase compensation at the two bands.(2).A dual-frequency quarter-wavelength transformer is discussed and further integrated into the branch-line coupler to implement the dual-band responses.(3).A dual-band power amplifier centered at 2.4 and 5.2 GHz is developed,and further,(4).Balanced power amplifier for dual-band application is developed and confirmed by EM simulations and measurements.In general,the dual-band phase shift power divider,3dB branch-line coupler and balanced power amplifier studied in this paper feature novel structure and good performance,making it potential in engineering applications.