Research And Production Of Highly Precise Frequency Synthesizer

Frequency synthesizing technology—the main component of radio electronics, is widely used in every field of radio-technology like communication, radiolocator, navigation, electronic reconnaissance. For the reason mentioned above, frequency synthesizer is the core part of many electronic systems.In recent years, people are increasingly strict with frequency synthesizer as its fast development. It shows up in the high qualification of output accuracy, nice electromagnetic compatibility, low electronic noise, short frequency-building time and so on. Customers usually need to use multiple frequency signals, and require higher standards to calibration, test, and frequency analog source.Based on the purpose of improving the degree of accuracy of frequency synthesizer, through the research of technology of frequency synthesizing, this paper provides a design plan of frequency synthesizer with high degree of accuracy. It also has conducted research on the core technology of frequency synthesizer from perspectives of technology of frequency synthesizing, referential design of frequency source, design of low-pass filter and so on.In the first place, according to the trend of the technology of synthesizing, this paper chose the frequency synthesizing chip AD9854 with direct digital frequency synthesis (DDS) rationally. This chip has some advantages of high frequency resolution, short transition time and nice spur suppression.In the second place, this paper analyzes the function of referential frequency source within a system according to the characteristics of input signals of frequency synthesizer. This paper also proposes that disciplined frequency standard reference source can be used as referential frequency source, due to the high accuracy, stability and reliability, because function of referential frequency source determines the quality of output signals. In the end, this paper designs the low-pass filter and corresponding amplifier, and accomplishes the global design of frequency synthesizer with high degree of accuracy against the characters of output signals.Making use of research results above, this paper builds a digital experimental platform of frequency synthesizer based on ARM, AD9864 and TDC. According to the test of core technology, the accuracy of this experimental platform is better than 5e-9, stability of which is better than 5e-10, this result satisfies the qualifications. Meanwhile, for the purpose of improving the plan, this paper also analyzes the factors that may influence the accuracy and stability of output signals.