Research Of K-Band Linear Channel Amplification Technology

With the continuous iteration and innovation of communication system technology,including new technologies such as more and more complex modulation methods proposed in recent years,the linearity requirements of the power amplifier have become more stringent.At the same time,Traveling-wave tube amplifier(TWTA)is widely used in communication systems due to its wide frequency band,high gain,and high power.Therefore,how to increase the linear power range of traveling wave tube so that the traveling wave tube can obtain greater power It has become a focus of research to ensure a low bit error rate while outputting.The Linear Channel Amplifier(LCAMP)is used in the driving stage of the traveling wave tube amplifier.It provides suitable adjustable input power for the traveling wave tube and has the effect of improving the linearity of the traveling wave tube.This article has studied and designed a LCAMP module that works in the 17.7?19.7GHz frequency band.First,based on the functions that the module needs to implement,three verification circuits are designed:1.Designed and processed a power level control circuit based on single chip microcomputer control.It has two working modes: Automatic Level Control(ALC)and Fixed Gain Mode(FGM).Both modes can achieve a gain adjustment range of 30 d B..Integrated temperature compensation function,when working at room temperature,the automatic level control mode can achieve constant output power in the dynamic range of input power-10?6d Bm,and the fluctuation is within ±1.1d B.In high and low temperature working conditions,the module power level control function can achieve constant output power within the dynamic range of input power-10 d Bm?-1d Bm,and the fluctuation is within ±3d B.2.Designed and processed a bridge reflection analog predistortion linearizer based on Schottky diodes,which can achieve amplitude expansion ? 8d B and phase expansion ? 42 °.The frequency consistency of the amplitude expansion(the difference of the amplitude expansion of different frequencies)is within 1.2d B,and the consistency of the phase expansion(the difference of the phase expansion of different frequencies)is within 15°3.Designed and processed an adjustable equalizer based on Schottky diodes.The amount of equalization can be adjusted within the range of 2.93 d B? 12.92 d B,and the equalization curve has a positive slope.Designed and developed an overall LCAMP module working at 17.7?19.7GHz,which verified the main functions required by the linearized channel amplifier.Two working modes have been tested: ALC mode and FGM mode.The ALC mode at room temperature can achieve stable output power with a dynamic range of input power from-36 d Bm to-6d Bm,and the accuracy is within ±1.1d B to achieve ALC(automatic power supply).In the level control mode,the gain changes by 31.5d B in steps of 0.5d B.In FGM(fixed gain mode),the gain is changed in steps of 1d B by 30 d B.Integrated temperature compensation function,the dynamic range of the input power of ALC mode is reduced to-23 d Bm?-18 d Bm in high and low temperature environment.The predistortion performance of LCAMP was tested,and the results showed that the overall amplitude expansion in the working frequency band was ?5.96 d B,and the phase expansion was?62°,which realized the theoretical verification of the LCAMP module.