Design And Implementation Of 6GHz RF Channel For Multi Domain Analyzer

Multi domain analyzer is a new instrument which can observe the signal to be measured from time domain,frequency domain,modulation domain and other fields.As the input conditioning circuit of RF signal in multi domain analyzer,the performance of RF channel has a decisive influence on the frequency domain measurement function and index of multi domain analyzer.Compared with the RF channel in the traditional spectrum analyzer,its main feature is to down convert the signal higher than 3GHz to the Nyquist frequency of the acquisition system through the local oscillator signal with fixed frequency,and then directly collect the signal,so that the system has the ability of broadband spectrum acquisition;and through the circuit structure of frequency band decomposition and subsection mixing,the input signal is divided into four overlapping frequency bands Subchannel,which widens the working frequency range of RF channel and ensures the lowest 1GHz real-time capture bandwidth.In this paper,the RF channel in the multi domain analyzer is studied.After scheme demonstration,circuit simulation and experimental verification,a 9kHz~6GHz RF channel is designed,which mainly completes the following work:1.Design verification of the scheme.This paper introduces the common types of spectrum receiver and the key indexes of RF channel,then according to the overall framework and design requirements of the project,puts forward the overall design scheme of RF channel,analyzes the functions of each circuit module in detail,and carries out the communication link simulation through ADS software.2.RF channel hardware circuit design.On the basis of the overall scheme,the selection of each key circuit of RF channel is completed,and the hardware circuit of RF channel is designed and implemented,including variable gain amplifier circuit,low noise amplifier circuit,power distribution circuit,mixing circuit,local oscillator module and filter bank.For each module,the key points of circuit design are described.At the same time,the power supply scheme and PCB design principle of RF channel are given.3.The design of amplitude equalizer based on RF channel.In order to improve the defect that the frequency response of the through path in the RF channel is not ideal,according to the measured results of the path,the corresponding amplitude equalizer is designed,the mathematical model and circuit model of the equalizer are analyzed,and the parameters of each element are determined through the joint simulation of schematic diagram and layout.The frequency compensation function of the equalizer is verified by the real test.Finally,the thesis designs and realizes 9kHz ~ 6GHz RF channel of multi domain analyzer,and tests the key indexes of RF channel.Among them,the direct path can achieve the real-time capture bandwidth of the highest 3GHz,the input standing wave ratio is less than 1.29 in 3GHz,and the noise figure is 15.16 db,which achieves the design goal.