The Design And Realization Of Small-step Low Spur Low Phase Noise Fast Hopping Frequency Source

The frequency source is the core component of modern electronic systems and equipment.With the rapid development of communication,navigation,guidance,electronic countermeasures,instrumentation and radar technology,systems and equipment have put forward higher and higher requirements for the performance of frequency sources,requiring them to have: broadband output frequency,high frequency resolution,Low phase noise,high spurious suppression,fast frequency switching,high harmonic suppression and other performance indicators,while also requiring modularity,miniaturization,low weight,Features such as low power consumption.This thesis addresses the problems of small frequency steps,poor spurs and phase noise,and long frequency hopping time for existing frequency sources,combined with theoretical calculations,simulation analysis,experimental verification and other research methods,and focuses on small frequency steps and low phases noise of frequency sources.In-depth research has been conducted on the design techniques of indicators such as high spurious suppression,and fast frequency hopping.The main research work of this thesis includes:1.Using two-stage fractional frequency-divided phase-locked loop cascade,variable reference,VCO selection and other frequency synthesis schemes,a small stepping,low spurious,low phase noise,and fast frequency hopping frequency hopping source 1 is designed.The output frequency range of frequency hopping source 1 is 3000MHz～4200MHz;frequency step 20Hz;spurious suppression 70 d Bc;harmonic suppression 40 d Bc;frequency hopping time≤35us;phase noise￡(@1k Hz)≤-90 d Bc/ Hz,￡(@1MHz)≤-120 d Bc/Hz;standing wave≤1.5.2.A frequency hopping source with low spurious,low phase noise and fast frequency hopping is designed by adopting frequency synthesis schemes such as fractional frequency phase-locked loop and VCO selection.The output frequency range of frequency hopping source 2 is 3200MHz～5000MHz;frequency step 1MHz;spurious suppression 70 d Bc;harmonic suppression 40 d Bc;frequency hopping time≤35us;phase noise￡(@1k Hz)≤-90 d Bc/Hz,￡(@1MHz)≤-110 d Bc/Hz;standing wave≤1.5.3.Using the frequency synthesis scheme of DDS and PLL output mixing,a small stepping,low spurious,low phase noise,frequency agile frequency hopping source 3 is designed.The output frequency range of frequency hopping source 3 is 4600MHz～4900MHz;frequency step 1Hz;spurious suppression 70 d Bc;harmonic suppression 40 d Bc;frequency hopping time≤1.8us;phase noise￡(@1k Hz)≤-90 d Bc/Hz,￡(@1MHz)≤-110 d Bc/Hz;standing wave≤1.5.In the end,the author completed a frequency source module with high technical indicators,modularity,standardization,low weight,low power consumption,etc.through reasonable circuit design,FPGA control program design,structural design,electromagnetic compatibility design,etc.The frequency source module contains the above-mentioned three different types of frequency hopping sources,and completes the generation,filtering,amplification and distribution of 14-channel frequency hopping source signals,external interface control functions,frequency control functions,and status management functions.