Research And Design Of Broadband High Linearity Power Amplifier Based On GaAs HBT Technology

To meet the ever-evolving demands for communication speed,capacity,and stability,the fifth-generation mobile communication network(5G)has emerged.As a critical component of the 5G communication network,communication base stations are rapidly evolving towards high information throughput and high data transmission rates.This presents higher requirements for the design of the radio frequency(RF)front-end,mainly in terms of increasing transmission power and work efficiency,enlarging the work bandwidth,and improving linearity.As the core active device of the base station RF front-end and the most power-consuming part of the transmitter,the RF power amplifier directly determines the performance of the RF front-end in terms of its work bandwidth,transmission power,efficiency,and linearity,which directly affect the distortion degree of the final transmitted signal.Therefore,designing a broadband,high linearity power amplifier is particularly important to meet the ever-increasing communication demands.This thesis firstly introduces the current research status of RF power amplifier at home and abroad in order to define the research scope of this topic.Secondly,the semiconductor technology used in this design is discussed in terms of operating principle and device characteristics.In addition,the basic theory of power amplifier is elaborated,and the difficulties of the power amplifier in this design are discussed.According to the analysis of above research,this thesis designs a broadband power amplifier suitable for 5G communication base stations based on GaAs HBT process.The main research work is summarized as follows:(1)A novel bias circuit is proposed to improve the linearity of the power amplifier.Because the traditional bias circuit cannot stabilize the quiescent operating point of the HBT device,the power amplifier produces nonlinearity.In addition,the traditional bias circuit has poor temperature stability and cannot achieve precise control of the current.The new bias circuit proposed in this thesis solves the above problems,and effectively improve the linearity of power amplifier,while achieving good thermal stability and accurate current control.(2)The design requirements of broadband and high gain are achieved by adopting the technology of equal Q value matching and the structure of multistage amplifier.A negative feedback network is added between the base and collector of the transistor to ensure good gain flatness in the design band according to the requirements of bandwidth and gain fluctuation.To ensure good electrostatic protection performance of power amplifier chip,additional electrostatic protection circuit is added to the chip.(3)A 2.3～5GHz broadband power amplifier is designed.The schematic diagram and layout design of the Die,the simulation design of substrate and test board,and the co-simulation of the chip are completed respectively.The simulation results of the designed power amplifier meet the expected criteria,and have been debugged by the fabrication and later stage.The test results have indicated that within the frequency range of 2.3～5GHz,the power amplifier exhibits a small signal gain of35d B,a saturated output power greater than 27d Bm,a power-added efficiency greater than 30%,and a compact chip size of only 0.576mm~2.Compared with relevant designs both domestically and internationally,the power amplifier designed in this thesis exhibits distinct advantages in terms of bandwidth,gain,and chip area.