The Design Of Wide Band Frequency Synthesizer Based On DDS And PLL

Frequency synthesizer is a key part of the modern electronic equipment. It canprovide the vibration signal and carrier signal for communication equipment.Thesesignals are accuratly and they can convert quickly.Since twenty or thirty times,frequency synthesizer has a history of about seventy years, it is the heart of theelectronic devices and plays a decisive role in the system. With the developments of thenational defense, military and communication industry, all fields demand higherimprovement on the frequency synthesizer: for higher output frequency, widerfrequency range, less frequency changing time, better signal purity, and less powerconsumption, smaller volume and so on.These all greatly accelerates the developmentsof frequency synthesizer.This article is based on a practical engineering project and introduces a design of abroadband, high-speed frequency synthesizer, the process of design is:first,designs theprinciple diagram of the systerm. The plan is that DDS produces the base signal, then itis mixed with the signal produced by pll to get the signal of2-18GHZ.It’sfrequency-changing time is less than one microsecond. It can give the signals with avariety of modulation.Second,this project will be divided to four modules by thefunction and then gives the principle and index diagram of each module.Also weselected the proper component.Third,Analysis and calculation results are given too. Wealso use software to simulation.The results gived by the simulation is compared to theresults tested.In the end,it gives the test results of whole system and the hardwarediagram.This article also describes the theory of the DDS and gives the reasons of theSpectrum degradation.It also gives the control method of DDS, including the steps ofcontrol and time diagram. It gives the method of simulation based on main components,and analysis the diagram. This product is used in the communication equipment of theship and airplane successfully.