Design And Implementation Of Rf Front-end Of Microwave Real-time Spectrum Analyzer

This paper aims to design a pair of DC ~ 20GHz(eventually realized as 27.8GHz)frequency range of the signal down conversion processing,the final frequency at 160 MHz meets the requirements of the miniaturization of high-integrated microwave real-time spectrum analyzer RF front-end receiver Machine module(hereinafter referred to as the receiver).In order to achieve the entire receiver module,this article has done the following specific work.By comparing the performance of various receiver schemes available in different applications,combined with the use and indicators of the receiver,the three-stage super heterodyne down conversion system scheme of the pre-preselected filter is determined.Each component is indexed.The receiver has a frequency range of DC ~ 20 GHz.However,if directly deal it with down conversion processing,the questions as following: It is impossible to filter out a part of the signal interference and harmonic interference,The local oscillator output frequency range is required very wide,which is a huge cost.So the frequency of the whole DC ~ 27.8GHz is divided into 13 small cases by considering the image rejection,the local leakage of the mixer and the leakage of the RF,the frequency range of the local oscillator,the spurious and other problems.Combined with the mixer's MN harmonic suppression table and the receiver system indicators,pre-filter indicators are integrated.Based on the theoretical analysis,it is proved that the suppression of the local oscillator leakage can be realized by the orthogonal modulation scheme,and finally it is verified by the physical test.Then,in this paper,the design of the module requires miniaturization,high integration and easy to carry,so designs of the intermediate frequency 4560 MHz and 2560 MHz with bandwidth 100 MHz,high sideband suppression of the two micro strip IF filters are realized.To avoid such as the cavity filter complex debugging process and harsh installation requirements,the filter printed directly on the PCB board,and became a model during the PCB board processing at the same time.On the basis of the completion of the various key components,this paper finished the selection,modeling,simulation for some key components.Finally,the schematic diagram of the whole system set up,and the modules of the previous chapters are integrated.The layout of the simulation and the final processing are given.The relevant indexes are analyzed and completed,and the system is expected to meet the requirements of the system.In this paper,the RF front-end receiver of the microwave real-time spectrum analyzer is decomposed into the design of every single component to achieve the final design of the whole machine,and the detailed design and implementation process are given.Finally,the relevant test indicators of the physical object meet the design requirements.Which indicates that design is realized successfully.