| The RF power amplifier is an important part of RF system transmission link,which is closely related to the whole system index.Due to the limitations of transistor devices,RF technology and circuit structure,the traditional RF power amplifier has the disadvantages of small coverage band range and insufficient power output.With the continuous development of wireless communication technology,the signal bandwidth is getting wider and wider,the peak average ratio,the application requires the signal long-distance transmission and the multi-band coverage of the same application platform,etc.,which puts forward requirements on the frequency band,power and linearity of the RF power amplifier.The traditional RF power amplifier has been unable to meet the requirements of the RF system,so the RF power amplifier with wide band,high power and good linearity has become a research hotspot.The L-band RF power amplifier module designed in this paper has the characteristics of wide band,high power and good linearity,and can be used in wireless communication or radar system transmission link.The transverse double diffused metal oxide semiconductor(LDMOS)transistor is used as the core device,and the DC parameters and impedance points of the power tube are obtained by the load traction system and probe station.The matching circuit adopts the broadband matching technology,and the frequency characteristics of microstrip transmission line and capacitive elements are used to achieve the broadband performance.Rf power amplifier module adopts three-stage cascade amplification signal,through analyzing the advantages and disadvantages of the basic circuit structure of various types of broadband RF power amplifier,the final stage RF power amplifier is selected as a balanced broadband circuit structure,which has the characteristics of broadband impedance matching and high power output.Four-port directional coupler is used at the end of RF amplifier module to realize power detection.AD software was used to complete the schematic diagram and layout of the RF power amplifier module,and finally completed the physical assembly,debugging and testing.The working bandwidth of the RF power amplifier module is 0.96GHz-1.4GHz.During the large signal continuous wave test,the maximum output power is 49 d Bm(80W),the power gain is greater than 40 d B,and the overall efficiency is greater than 35%.For the linearity test,the output power is greater than 40 d Bm(10W)when the power regression is 9d B,the adjacent channel power ratio(ACPR)is better than-40 d Bc,the error vector amplitude(EVM)is better than-35 d B,and the thirdorder intermodulation coefficient(IMD3)is better than-30 d Bc.The test data show that the RF power amplifier module can be well applied in radar or wireless communication transmission link,and has good engineering application value. |
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