Research On Highly Stable Freauencv Synthesis Technology With Fast Frequency Regulation

Microwave measurement has the advantages of not being easily affected by the environment,wide frequency range,strong penetration ability and Anti-low frequency interference capability,etc.It has a wide range of applications in many fields.As the core component of the microwave measurement system,the frequency source is directly related to the quality of the microwave measurement system.As the application scenarios of microwave measurement systems become more and more complex,performance requirements such as measurement accuracy become higher and higher,and requirements for frequency resolution,frequency regulation rate,and frequency stability of frequency sources become higher and higher.Aiming at the problem that the three performance indicators of frequency resolution,frequency regulation rate,and frequency stability cannot be taken into account,this thesis starts a research on high-stability frequency synthesis technology that can quickly regulate the frequency,and develops a technical solutions for driving a phase-locked loop with a direct digital frequency synthesizer.Based on the formulated technical solution,through theoretical analysis and simulation of the frequency regulation rate and frequency stability,a high-stability frequency source capable of rapid frequency regulation was realized,and experimental verification was completed.The main research contents of this thesis include:1)Research on frequency synthesis solution.Aiming at the research goals of frequency sources with high frequency resolution,high frequency regulation rate,and high stability,various types of frequency source design methods are analyzed.Finally,a frequency source that satisfies the three performance indicators of frequency resolution,frequency regulation rate,and frequency stability is designed by research,and a specific frequency synthesis solution is formulated.2)Research on High Dynamic Performance Frequency Synthesis Technology.The dynamic performance of the frequency source refers to the frequency regulation rate,and the high dynamic performance frequency source can quickly regulate the frequency.This thesis uses the sine frequency modulation rate of the system output signal to characterize the frequency regulation rate of the system.This section analyzes the steady-state tracking error of the phase-locked loop,the steady-state tracking limit of the phase-locked loop,the analysis of the steady-state error of the phase-locked loop with different loop filter types,and the limit estimation of the frequency regulation rate.In the end,it is concluded that the frequency regulation rate is mainly affected by the output peak frequency offset,the loop filter type,and the phase detector type,and the loop filter type with the best tracking performance and the widest phase detector type are determined.3)Research on high stability frequency synthesis technology.This section analyzes the frequency stability of the output frequency signal of the system theoretically,finds out the factors that affect the phase noise and spurs.It is concluded that the output spur of a direct digital frequency synthesizer depends on the normalized frequency,and the phase noise performance of the phase locked loop mainly depends on the loop bandwidth and damping coefficient.Finally,based on the conclusions,a reference frequency reference generation solution was determined,an improvement method for DDS spectrum purity,and a phase-locked loop phase noise suppression method were found.The above research content was finally verified by building an experimental platform and performing performance tests on the experimental prototype.Test results show that the system can achieve high frequency resolution,high frequency regulation capability and high frequency stability.