The Design Of S-band Linear RF Power Amplifier

Power amplifier is an essential module for microwave radio frequency communication system,the performance of power amplifier will directly affect the performance of the transmitter.Especially with the development of wireless communications today,wireless communication system has made higher requirements of power amplifiers,such as high efficiency,broadband,linearity and so on.To combine with the requirements of today's communication system,an S-band broadband RF linear power amplifier will be designed in this thesist.In the first chapter of this thesis,the research background of power amplifier and the development of linearization technology are summarized.The second chapter lists the types of RF power amplifiers and briefly analyzes the working principle of each power amplifier.At the same time,the main performance metrics of the power amplifier are briefly introduced.Then the respective characteristics each of several linearization techniques will be introduced and analyzed.After understanding the basic concept of power amplifier and linearization technology,the theory of broadband RF power amplifier will be introduced in the third chapter.After analyzing the matching network of power amplifier,the scheme of RF power amplifier is analyzed.Finally,this thesis will adopt matching network compensation to achieve a two-cascade power amplifier.Using a ADL5321 chip as a driver power amplifier to push input signal to meet the final power amplifier's requirements,the final output power amplifier using CREE's CGH40010 which is a GaN high electron mobility transistor,in order to ensure the power amplifier's linearity will be biased in Class AB operating state.According to the parameters and model given by the device,ADS simulation is performed.The simulation includes the transistor's DC sweep,input and output impedance analysis and matching network design,especially using the microstrip line as matching network.There are some questions about drawing PCB board,including the design of DC circuit,some rules of board layout and wiring and the design of the heat sink after the completion of the simulation.Finally the operating frequency range is about form 2.4GHz to 3.6GHz,bandwidth up to 40%,output power is 33 dBm.In chapter 4,the linearization technique is introduced briefly.In this thesis,analog predistortion technology will be used.After analyzing and simulating three kinds of analog predistortion structures,a single diode pre-distortion network with bias can adapt to the broadband RF power amplifier,in the center frequency of 3.0GHz,50 MHz offset,can effective suppression of 17 d B third-order intermodulation distortion;T-type network with the reverse parallel diode network can adapt to broadband power amplifier,but it has a large power attenuation;Although the bridge of the composite reverse parallel diode network can play a better linear,but it can not adopt to broadband power amplifier.