Design And Implementation Of RF Front-End For Broadband Zero-IF Systems

In recent years,wireless communication technology has become an indispensable part of people's lives.With the development of wireless communication technology,the demand for communication services is also increasing.Wide bandwidth,simple structure,low power consumption and generalization are inevitable trends in the development of RF front-end technology.In order to meet the related needs of the communication business,it is also crucial to choose a suitable frequency conversion structure.Spectrum shift is one of the core of wireless communication technology.For the traditional superheterodyne frequency conversion structure,it requires multiple spectrum shifts to meet the demand,which inevitably leads to an increase in cost,space,and power consumption.The zero-IF frequency conversion technology only needs one spectrum shift to realize the function.However,this frequency conversion structure will cause IQ(in-phase/quadrature)imbalance and DC bias.Therefore,the rational design and implementation of the RF front-end of the broadband zero-IF system had certain research value and significance for the wireless communication technology of the broadband RF front-end.The thesis takes wireless Ad-hoc networks and software radio as the research background of the subject,and focuses on the design and implementation of the RF front-end of the broadband zero-IF system.The main research contents are as follows:(1)In response to the needs of the broadband networking design,a radio frequency front-end solution for a broadband zero-IF system with duplex transmission and reception was designed.This solution completes the selection of zero-IF system chips and budgets for key technical indicators.The working frequency band of the transceiver system in the scheme supports 1?4GHz,and the working bandwidth can reach 500 MHz,which can be applied to the broadband RF front-end of general software radio.(2)For the designed RF front-end solution,the hardware circuit design,schematic drawing,PCB production are completed,and the completed RF front-end hardware is combined with the digital platform to realize the collection and generation of broadband communication signals,and finally realized Broadband communication radio frequency signal reception and transmission wireless communication function.(3)Aiming at the problem of IQ imbalance and DC bias caused by the zero-IF structure in the receiver,two IQ imbalance compensation algorithms and a DC offset estimation algorithm are designed in the digital domain.Simulation results show that the algorithm can effectively calibrate the IQ imbalance and eliminate the DC bias compared with the data not processed by the algorithm.The actual circuit is used to collect the digital output signal of the ADC,and the algorithm verification is completed.The results show that the single-frequency IQ imbalance compensation algorithm can increase the image suppression by 15 d B,and the multi-frequency IQ imbalance compensation algorithm can increase the image suppression by 3d B.The DC bias estimation algorithm improves the DC bias signal suppression by 5d B.(4)Combing with the field-programmable gate array digital verification platform and experimental test instruments,the performance parameters of the RF front-end of the broadband zero-IF system were tested,including power supply,receive channel performance,transmit channel performance,IQ imbalance compensation algorithm,and DC bias.Compared with needs of broadband networking design,this design solution can meet the design's index requirements.