Realization On Ultra Wideband Frequency Synthesizer With Low Phase Noise

Frequency synthesis and PLL technology are widely used in Communication,Remote control and instrument fields. Designing of wide-band frequency synthesizer isa key point. With the development of system requirements, the target of frequencysynthesizer is getting higher and higher. Realizing of high spur rejection and low phasenoise with ultra wideband and high frequency resolution become urgent.This paper is according to the practice requirements of frequency synthesizer in aKu-band receiver in a project. Combining of the requirements of the task, a ultrawideband frequency synthesizer with low noise is designed. The mostly working andfruits are as follows.At first the status and developments of frequency synthesis technology areintroduced. A description and comparison of basic principles and realizing of generalfrequency synthesis methods are proposed. Emphasized the analysis of phase noise andspur characteristic of PLL, frequency mixer and frequency multiplier.Based on comparing the specialty of each synthesis mode, and the target of phasenoise, spur rejection, size and power consumption, a scheme of frequency mixing PLLwith frequency multiplier is shown.According to the characteristic of the scheme, each module of the system isanalyzed and researched. An experiment on the technology is operated in order to verifythe new method, including electronic component choosing, target estimating, circuit andPCB designing, assembling and debugging, realized the target of the task, proved thefeasibility of the scheme.The ultra wideband low noise frequency synthesizer discussed in this paper workswell in system application, showed excellent performance. Now it is produced in batchin another important project, provided widely applicable foreground.