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Design >> RF Design >> puzzle about phase noise
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Message started by devin on Apr 10^th, 2008, 5:49am

Title: puzzle about phase noise
Post by devin on Apr 10^th, 2008, 5:49am

Hi, all

I have some questions about phase noise, would someone help me? :D
1. In the so-called nonlinear osc, amplitude noise or AM noise can be neglected in the basic analysis in many classical books and papers, and we can speak that the skirt of the frequency spectrum totally come from phase noise. However, in the factual circuits like ring-osc, colpitts or cross-coupled LC osc, etc, can we really regard all the skirt of the frequency spectrum due to phase noise?
2. If there is some amplitude noise for the skirt of frequency spectrum, then how can the simulation tool like spectreRF tell the accurate proportion of the noise that comes from phase noise in its pnoise simulation. Because I'm curious about how spectreRF divide the noise into AM part and PM part?
3. Can someone give me an intuitive explaination about the calculation of phase noise or give me some documents and papers for the method to calculate phase noise?
Thanks in advance:)
Thanks.

Title: Re: puzzle about phase noise
Post by chenyan on Apr 10^th, 2008, 5:54am

Close to carrier VCO noise is mainly phase noise. therefore Am noise can be neglected.
In SpectreRF, you can seperate the noise skirt into AM and PM by set noise type "modulated"