Research On Wideband RF Front-end In RF Simulation System

The application of RF simulation system can reduce time period and development costs of weapon equipment and improve development efficiency,and it plays an irreplaceable role in the weapon development process.The wideband RF front-end has a direct impact on the performance of RF simulation system.It is of great practical significance to develop a wideband RF front end with high dynamic range,high spurious rejection and low noise figure.This thesis studies a wideband RF front-end in the RF simulation system is applied in the S-band,whose main function is to convert the received signal into low intermediate frequency.The intermediate frequency output of this RF front-end is 0.1GHz~1.1GHz,and its relative bandwidth reaches 167%.Under this condition,the realization of low spurious and excellent passband characteristics faces very high technical difficulty.In this thesis,the wideband RF front-end in the RF simulation system is studied with the background of the application in detail.The thesis studies a double-conversion superheterodyne receiver,and analyzes frequency components which are produced in the process of down conversion.The components in the system are designed reasonably and the parameters of the components are allocated,and the whole link simulation is used to optimize the components indicator requirements.The wideband low noise amplifier,bandpass filter,double-balanced mixer,IF bandpass filter and power amplifier are designed and simulated by using ADS and HFSS,and these devices are made and tested.In order to achieve low-spurious RF wideband front-end indicators,transmission zeroes are designed in bandpass filter to improve filter selectivity and out-of-band rejection and the interference of combined frequency is decreased by using the double-balanced mixer.The wideband devices are made and tested.Solution is given for the problems found in testing with rational theoretical analysis.According to the test results,the spurious signals involved in the system output are lower than-40 dB,and gain flatness is ±2.1dB.As a result,the technical requirements of Wideband RF Front-end in RF Simulation System are basically satisfied.