Research And Design Of X-band FMCW Transceiver Front-end

Frequency modulated continuous wave(FMCW)radar has many advantages compared to single frequency continuous wave radar and pulse radar.The FMCW transceiver front-end is an important part of the FMCW radar.Its performance has an important impact on the FMCW radar.And the X-band antenna has a small size and high range and azimuth resolution,which is conducive to the detection of close-range targets.Therefore,the research on X-band FMCW transceiver front-end has very important significance.This article mainly introduces the design and implementation of an X-band FMCW transceiver front-end.First,it compares and analyzes the advantages and disadvantages of several common frequency source technologies and receiver technologies.According to the index requirements of this subject,this design proposes that the transmitter uses a phase-locked loop chip to generate a wide-band FMCW,and the receiver uses a zero-IF receiver circuit design scheme.The frequency source module is a phase-locked loop circuit composed of crystal oscillator,phase detector,active loop filter,VCO,and lownoise amplifier.It generates low-phase noise and low-spurious 8.2-12.2GHz FMCW.Through amplifier and power divider,it is divided into two channels,one is used as a radio frequency signal for transmission,and the other is used as a local oscillator signal in the receiving module.The receiving module mixes the received radio frequency signal with the local oscillator signal to generate a IF signal including measurement information,and then it's filtered,amplified and so on.According to the disadvantage of slow frequency conversion when using PLL chip to realize FMCW frequency source,this paper briefly introduces the design and implementation of a millimeter wave band FMCW frequency source using DDS + PLL frequency source technology.In the process of introducing X-band FMCW transceiver front end,the circuit design process is analyzed in detail,and the performance of each module and the cascaded circuit is tested.The test results show that the transceiver front-end can achieve the following targets: adjustable bandwidth(3-4GHz)of the output FMCW,adjustable modulation period(>1ms),transmission power >15d Bm,external acceptance gain control,output IF amplitude ?3.3Vpp,etc.The transceiver front-end studied in this paper provides a RF front-end solution with simple structure and good performance for X-band FMCW measurement radar.