Design and Realization of L-Band FH Synthesizer
Han Li · Journal of Beijing Institute of Technology · 2000
An L band frequency hopping synthesizer that is provided with performances of fast frequency hopping and low phase noise was designed, the project of fast pre setting to VCO by DAC circuit was adopted, and a very short frequency switching time was got. Through optimizing loop division factor N and reference division factor R , making output frequency of FH synthesizer have a non linear relation with loop division factor N , namely adopting frequency hopping with non uniform frequency step,the output phase noise caused by bigger N can be reduced. When a general crystal was used in reference frequency source, the result of measurement is as follows: the frequency switching time is less then 10 μs, the output SSB phase noise spectrum density is about -70 dB/Hz at 1 kHz offset.