Low Phase Noise Low Stray C-band Frequency Source

With the developing of communication and radar system, the demand on trans- receiver system increases every day, and frequency sources which provide LO(local oscillator) signals to trans-receiver systems is also needed This thesis dedicates to research the characteristics of C-band frequency source with low phase noise and low spurious output, and the analysis of the experiment results is given.This thesis firstly presents the development of microwave frequency sources with low phase noise and low spurious output, and the principle of frequency source is analyzed. Secondly, the definition and type of phase noise is described, and the effect by phase noise on trans-receivers is introduced either. The characteristic of phase noise output of oscillator and the effects on phase noise by frequency multipliers and amplifiers are also analyzed. At the same time, the theory of using a double-balanced mixer to make frequency multiplying is explained and a practicable multiplier-source plan to realize very low phase noise output is provided. The spurious output of multiplier-source is analyzed explicitly and some methods of suppressing spurious components are suggested too. Meanwhile, a C band source with very low phase noise and spurious output is developed, which has a good performance at 5760MHz with phase noise output less than -115dBc/Hz at 10kHz offset, suppression of spurious output better than -81dBc and output power more than 10dBm. Furthermore, a C band up-converter module is developed, which outputs at 5910MHz with spurious suppression better than 80dBc and output power more than 10dBm. The two modules can be used as referenced sources of higher frequency band sources.This thesis also presents the principle of a PPL source with low phase noise. First, the development, basic theory and main structure of a PPL source are explained, and the effect of characteristics of phase noise from each part of a PPL is discussed. Second, the spurious output of a PPL is analyzed, and some methods to achieve low spurious output are suggested. Meanwhile, a stable and compact size S band PPL source with low phase noise is developed. It has a good performance at S band with very low phase noise less than -106dBc/Hz at 10 kHz offset and suppression of spurs better than 63dBc. The output power is more than 10dBm. This module is suited to provide the second LO of receivers which work at higher frequency band.The test results indicate that the C band and S band module has very satisfied output characteristics of very low phase noise and high suppression of spurs, and verify the plan's feasibility.