Study On Microwave Multi-band Low Spurious Low Phase Noise Of The Local Oscillator

The frequency synthesizer is a very important component of virtually anymicrowave test-and-measurement systems, communication systems, and monitoringsystems. With the attention of various countries and invested heavily, frequencysynthesizer has made great achievements. Currently, the design of high-performancefrequency synthesizer is still the hotpot.Starting from the research background of frequency synthesizer, this dissertationintroduces the frequency synthesizer developments at home and abroad, and thendescribes the main technical indicators of the frequency synthesizer and theclassification of frequency synthesizer. On this basis, according to the requirements ofthe issues indicators L, S and K-band frequency synthesizers programs, and analyses thephase noise and spurious performance in theory, demonstrating the feasibility of theprograms. Taking into account the low cost and miniaturization design, the L andS-band local oscillators ultimately use based on the chip of integrated VCOphase-locked-loop frequency synthesizer program design, specifically including thepower supply design, the design of the loop filter, the overall circuit design andsoftware debugging and its basic theory. Because of K-band frequency synthesizer phasenoise requirements higher, the selection of the program is particularly important; First,the design and analyze of the specific programs based on the key components comefrom program select and feasible analyze, then the overall circuit design, including the1.08GHz frequency multiplier module,9.6GHz multiplier module, phase+loop moduleand VCO+down-conversion module design. Finally, in order to meet the broadbandspurious indicators and index requirements of the output power, the output terminationshould have filter+amplifier circuit.The measurement results show that L-band local oscillator phase noise is betterthan-117dBc/Hz@10kHz,and spurious suppression is better than85dBc,and harmonicsuppression is better than24dBc,output power3dBm, achieves the target requirementsand realizes low-cost and miniaturization design; S-band local oscillators achievesphase noise-113dBc/Hz@10kHz,spurious suppression above82dBc, harmonic suppression better than24dBc,isolation of43dB above, the output power2dBm more,which are superior to the technical specifications requirements, while achieving alow-cost, miniaturized design; K-band frequency synthesizer based on the keycomponents of the three programs design and the experiments verified the phase noise canreach-106.98dBc/Hz@10kHz,and spurious suppression is better than82dBc in2GHzbandwidth, achieving the goals of low phase noise and low spurious, and VCObulit-in16divided leak spurious suppression is better than54dBc;In order to meet thebroadband spurious performance requirements and output power indicator requirements,the need for further research to filter+amplifier circuit module design. In short, theissues has verified the feasibility of the programs, achieved the expected goals of theissues.