Design Of The Signal Source Of Linear Frequency Modulation Radar Based On DDS

As a key component of the information society,remote sensing systems,radar detection,aircraft and aerospace,electronic communications,and other fields are all research hotspots,which also require corresponding improvements in the performance and technology of frequency sources.With the overall development of the fifthgeneration mobile communication technology and the microelectronics industry,highquality signal sources and advanced frequency synthesis technologies also have broader application prospects and demands.At present,the frequency band,phase noise,spurious,output power,frequency hopping speed,and frequency stability are important basis for evaluating the overall performance of the system,and the quality of the frequency source system also limits the upper limit of the circuit system.This thesis first starts from the various performance indicators of the frequency source,and focuses on the analysis of important technologies related to the phase-locked loop and its frequency synthesis,and the direct digital synthesizer.By comparing their characteristics,several commonly used hybrid frequency synthesis schemes are further introduced,which provides reference and basis for the research of this subject.Then,the demand analysis of the related technical indicators of the subject frequency source was carried out,and the related design architecture was screened.Finally,the system synthesis scheme of DDS+phase lock loop chip was adopted.It combines the advantages of the two,so that the resolution and step of the output signal frequency can be very fine,the frequency jump is fast,the phase noise is excellent,and the filtering and control design are simple.Specifically speaking,the crystal oscillator generates a lower fixed frequency signal as the clock reference signal for the chip and other circuit modules.Next,a singlechip microcomputer development board is used to control the phase-locked loop and the direct digital synthesis chip.Let the two PLL circuit modules output different proposed point frequency signals as the external clock and upmix frequency standard of direct digital synthesis,and the other DDS modules generate linear frequency modulated continuous wave signals.Finally,after up-mixing,amplifying and filtering the generated LFMCW,the LFMCW signal of the target frequency band of this thesis is realized.After the design plan was drafted,reasonable options were selected according to the design indicators,and the design simulation of the power divider,the small signal amplifier,and filter used for clock driving in the system was completed,and then the frequency source system of this thesis was moduled according to the function.On this basis,complete the circuit design of different modules such as logic control,phase-locked loop,direct digital frequency synthesis,power supply,etc.,and then rationally layout and route the overall circuit layout,complete the physical design and processing of the system,and use the frequency spectrum The instrument and other instruments have carried out corresponding circuit debugging and system testing,compared and analyzed the test results with the design goals,and finally completed the overall requirements of the project.On the whole,this topic is based on the theory of frequency synthesis,from the system plan to the circuit design and processing,the final circuit is obtained,and the output of the LFMCW target signal of 2-2.167 GHz is comprehensively realized,and the corresponding frequency source system index Also met expectations.