Design And Implementation Of Miniaturized S-band Wave Radar Frequency Synthesizer

With the development of marine scientific research,radar equipment has become one of the essential equipment for marine exploration.As the core of the radar system,frequency synthesizer directly affects the overall performance of the entire system.With the acceleration of electronic product updating and iteration,the performance requirements of frequency synthesizers for radar systems are gradually increasing,and they are constantly developed towards wide bands,low spurs,fine stepping,and miniaturization.Based on the research background above,this paper describes the development of a miniaturized frequency synthesizer applied to the S-band Doppler wave radar system according to the requirements of the S-band Doppler wave radar system of Wuhan University's Radio Ocean Remote Sensing Laboratory.The thesis first introduces the current mature frequency synthesizer design structure,and briefly describes the principle,advantages and disadvantages of the related,and compares the performance of different schemes through a list.Then,the design of the frequency synthesizer adopted in this paper is determined according to the requirements of S-band Doppler wave radar system.Through device selection and parameter calculation,the feasibility is further discussed.The circuit of the frequency synthesizer is designed with a modular idea and is.Divided into three parts according to the requirements of the system output signal: the first local oscillator part,the second local oscillator part and the RF excitation part.Then,subdivide each part of the circuit into DDS circuit part,PLL circuit part,clock circuit part,power supply part and radio frequency circuit part.Then again,the circuit design and schematic drawing of each part of the circuit are carried out in sequence,and the circuit design of DDS and PLL is completed with the aid of ADIsim DDS and ADIsim PLL software.According to the drawn schematic diagram,the PCB is designed,and its layout and routing are strictly in accordance with the mixed digital-analog design rules and RF circuit design rules.Then,use Polar Si9000,ANSYS SIwave,ICEPAK software to simulate and analyze the PCB's characteristic impedance,S-parameters,electromagnetic performance,heat dissipation performance and other related parameters to ensure accuracy of the design.After the circuit design and simulation were completed,the shield box is also designed with Solidworks and the electromagnetic field distribution as well as the resonance frequency of the box is also calculated with Electronics Desktop in the Ansys Electromagnetic Suite to ensure the shielding effectiveness.Finally,the welding,assembling and debugging of the designed frequency synthesizer are finished.After the debugging is completed,the test results of various indicators of the three output signals are given,including amplitude measurement,phase noise measurement,signal-to-noise ratio measurement,and sweep bandwidth measurement,and the corresponding test results are analyzed and summarized.From the test results,all the index parameters of this frequency synthesizer have reached the design requirements.The integration of digital circuit modules and analog circuit modules has successfully reduced the 8.8 × 48.3 × 35 cm modules to 2.6 × 8.6 × 13.4cm modules,which effectively reduces the volume of system equipment and improves the flexibility of equipment application.