X-band Frequency Synthesizer

Frequency synthesizer has played an important role in the electronic system. The fast development of the electronic technology is bringing forward higher request for frequency synthesizer. A frequency synthesizer with fast frequency switching speed, high frequency resolution, wide bandwidth, low phase noise and good SFDR has been paid much attention to. Therefore, this subject is to study the relative performance of the X band frequency synthesizer.This thesis gives an introduction about the development of frequency synthesizer, the basic theory and the advantage of PLL and DDS. A scheme using double phase locked loop is adopted to carry out the X band frequency synthesizer. The way to realize the synthesizer, the method to debug the system and the testing result are all mentioned in the paper.This project uses DDS+PLL as the local oscillator system and the output signal is 700～1200MHz. This method combines the advantage of DDS, such as high frequency resolution, fast frequency switching speed and high frequency accuracy, with the good performance of the phase locked loop. The signal from the primary phase locked loop is mixed with the local signal and the system finally output 8～12GHz signal. This thesis gives a detailed introduction about the function of each part, the design of EMC and the principle to choose chips. There is a specially introduction about the programme control flow, the design of PLL and the hardware interface circuit between SCM and DDS. Experimental result shows the phase noise performance, frequency switching time and picture of spectrum with spur. The output frequency ranges from 8GHz to 12GHz, phase noise is better than -67.9dBc/Hz@10kHz and the frequency switching time is 32μs. The result also shows that the spur performance can not satisfy the anticipation and the reason is given. At last the existing problem and the method to resolve it are mentioned.