Broadband Frequency Synthesizer Design

The wide coverage of the frequency synthesizer is used in modern communicationelectronics industry widely, especially in the communication signal source, the sourceof interference as well as ultra-wideband frequency hopping communication systemapplications. So far, how do stray wide coverage conditions, the balance between thevarious indicators of the phase noise and power flatness is an urgent problem of thewide coverage of the frequency source. Frequency synthesizer technology is moving inthe development of DDS direct synthesis and DDS+PLL complex frequencysynthesizer way.According to the needs of designing the system, DDS direct synthesis is slected toproduce the output frequency of local oscillator signal in the low frequency part, and inhigh frequency components, in order to meet the indicators of the design, DDS+PLLthat DDS is used for the PLL’s reference frequency is used to produce the localoscillator frequency source signal. The design focuses on how to do the DDS in the caseto ensure that the hopping time and the output signal accuracy, and the output signal toreach the needs of design spurious and phase noise indicators, and achieve broadbandoutput. DDS direct synthesis and DDS+PLL combination synthesis are used to designthe whole system in this article, and verified through experimental results, and finallythe result shows the feasibility of the above-mentioned frequency synthesis method inthe actual design practice. The design of ultra-wide coverage of the frequency source isa key technology for modern electronic systems.This article is mainly for broadband local oscillator signal element analysis andresearch. First,it introduces the development history, basic principles and characteristicsof the frequency synthesizer.Then it analyzes all kinds of the performance indicators ofthe frequency synthesizer in detail, and finally it gives the principal design of thefrequency synthesizer’s hardware and software. On the basis of the above preparations,the authors analysised the various frequency synthesizer methods and compared themeach others,and planed frequencies needed by the local oscillator. According to the system’s performance indicators, this article gives a specific design finally. At the sametime, the authors analysised the various key circuit design and key components carefully.Finally,it gives the circuit layout, signal isolation, implementation and system testresults.This paper puts forward the following key technologies and gives the sovlesolution of them:(1) It gives the performance analysis of the frequency synthesizer, and gives theprinciple of selection of proposals and devices.(2) Combining the project given the performance indicators, designed to meet therequirements of the frequency synthesizer.(3) For the design of frequency source with the broadband and low phase noise andfrequency hopping, this paper provides a good theoretical analysis,and it has acertain guiding significance.