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https://designers-guide.org/forum/YaBB.pl Measurements >> RF Measurements >> how to measure phase noise of PLL? https://designers-guide.org/forum/YaBB.pl?num=1241917016 Message started by liletian on May 9th, 2009, 5:56pm |
Title: how to measure phase noise of PLL? Post by liletian on May 9th, 2009, 5:56pm Hi Guys I would like to measure phase noise of my PLL, I had spectrum analysize, is there a tutorial how to measure phase noise? Thank you |
Title: Re: how to measure phase noise of PLL? Post by pancho_hideboo on May 9th, 2009, 6:38pm liletian wrote on May 9th, 2009, 5:56pm:
If you mean "Spectrum Analyzer", show me product number and options you have. If you have "Phase Noise Measurement" option, measuring phase noise is very straightforward. However I don't think your PLL can reach to valuable level to evaluate phase noise. Do you understand "Comparison Frequency" ? http://www.designers-guide.org/Forum/YaBB.pl?num=1241452951/8#8 |
Title: Re: how to measure phase noise of PLL? Post by liletian on May 9th, 2009, 7:08pm pancho_hideboo wrote on May 9th, 2009, 6:38pm:
If you mean "Spectrum Analyzer", show me product number and options you have. If you have "Phase Noise Measurement" option, measuring phase noise is very straightforward. Agilent N9020A However I don't think your PLL can reach to valuable level to evaluate phase noise. Do you understand "Comparison Frequency" ? not really yet, if you can explain, I will appreciate it. thank you |
Title: Re: how to measure phase noise of PLL? Post by pancho_hideboo on May 10th, 2009, 8:47am liletian wrote on May 9th, 2009, 7:08pm:
http://www.home.agilent.com/agilent/product.jspx?cc=US&lc=eng&ckey=842945&nid=-34679.385169.00&id=842945 If you have this N9068A, measuring phase noise is very straightforward. liletian wrote on May 9th, 2009, 7:08pm:
Other people who is very kind and patient will help you. |
Title: Re: how to measure phase noise of PLL? Post by rfmems on May 10th, 2009, 11:18pm Hi liletian, In your pll, you vco frequency has to be divided and then compared in PD/PFD with your reference. I guess you are desiging/measuring a pll with external loop filter, if that is the case, please read dean's book, availble at http://wireless.national.com. |
Title: Re: how to measure phase noise of PLL? Post by love_analog on Apr 27th, 2010, 9:26pm Just use a spectrum analyzer. Put your PLL output in it and the spectrum analyzer will give you exactly the phase noise at each frequency point in dbc/Hz |
Title: Re: how to measure phase noise of PLL? Post by pancho_hideboo on Apr 28th, 2010, 8:52am love_analog wrote on Apr 27th, 2010, 9:26pm:
It is a CNR not true phase noise if you use conventional Spectrum Analyzer without phase noise measurement option. First, you can't measure CNR for very small offset frequency if you use conventional Spectrum Analyzer. Second, it is no more than normalized sideband noise not PM noise if you use conventional Spectrum Analyzer. See the followings. http://www.designers-guide.org/Forum/YaBB.pl?num=1050465395/22#22 http://www.designers-guide.org/Forum/YaBB.pl?num=1256925601/4#4 |
Title: Re: how to measure phase noise of PLL? Post by love_analog on May 1st, 2010, 8:51am I need a little education here because that is what I have been using throughout. I understand a spectrum analyzer cannot distinguish between AM and PM noise. However, typically AM noise is at a much higher frequency >> 1Mhz so I do not care that much about the split at ~1Meg My understand was the dbc/Hz read is really the phase noise. What is CNR? In a practical scenario, how much difference is there between the "real" phase noise and the reading from a spectrum analyzer. |
Title: Re: how to measure phase noise of PLL? Post by pancho_hideboo on May 1st, 2010, 9:17am love_analog wrote on May 1st, 2010, 8:51am:
It is no more than C/N0 ; Carrier Power to Noise Power Density Ratio love_analog wrote on May 1st, 2010, 8:51am:
Noise Marker Mode in conventional Spectrum Analyzer shows C/N0 or C/N. love_analog wrote on May 1st, 2010, 8:51am:
I can't measure C/N0 at small offset frequency correctly using conventional Spectrum Analyzer. I have many instruments as well as EDA tools. When I have spare time, I will create actual measurement examples. We can't measure Carrier Power correctly because we can't separate carrier and noise clearly in actual measurement. On the other hand, carrier and noise are evaluated separately in small signal noise analysis subjected to master steady state large signal analysis such as Cadence Spectre PSS/Pnoise. |
Title: Re: how to measure phase noise of PLL? Post by love_analog on May 1st, 2010, 9:52am Now I know what you are saying. Yes, spectrum analyzer measures Sv(f) whereas what we really want is Sphi(f). 2 Question a) Apart from very close to center frequency, these 2 quantities should be the same? Although I realize that "very close" is not well defined but I presume its a few KHz of the center, or maybe its the point where Sv(f) is flatenning out b) If I am wrong, what method do you suggest to measure phase noise (if we do not use a spectrum analyzer) thanks |
Title: Re: how to measure phase noise of PLL? Post by pancho_hideboo on May 4th, 2010, 12:11pm The followings might be useful for someone. http://www.thegleam.com/ke5fx/gpib/pn.htm http://www.thegleam.com/ke5fx/gpib/readme.htm |
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