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The Designer's Guide Community Forum
https://designers-guide.org/forum/YaBB.pl Simulators >> RF Simulators >> True Sphi Plot in Cadence ? https://designers-guide.org/forum/YaBB.pl?num=1260521995 Message started by Mayank on Dec 11th, 2009, 12:59am |
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Title: True Sphi Plot in Cadence ? Post by Mayank on Dec 11th, 2009, 12:59am Hi, I am doing a phase noise analysis in cadence [ IC6.1.3 ] spectre [ MMSIM7.1 ] LΦ plots are inaccurate below the linewidth as it shows more than 0dBc/Hz phase noise which is irrelevant. I want to obtain a true SΦ plot in cadence...How can i obtain that ?? As Pancho pointed out earlier in one of his posts, http://www.designers-guide.org/Forum/YaBB.pl?num=1244213153/6#6 & i quote Quote:
When i simulate both pnoise sources and pnoise modulated, I get the same plots for both i.e. Phase Noise in pnoise option in sources analysis & Phase Noise in pnoise Jitter option in modulated pnoise analysis. This is not in accordance with pancho's statement in the above mentioned quote...I am confused again. Can anyone tell me how to get the True SΦ plot in cadence ? -- regards, Mayank. |
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Title: Re: True Sphi Plot in Cadence ? Post by pancho_hideboo on Dec 11th, 2009, 1:32am Mayank wrote on Dec 11th, 2009, 12:59am:
Using noisetype= "modulated" or "jitter", you can get SΦ(f). - You can get SΦ(f) as "2*PM noise" in "pnoise modulated of Direct Plot Form". - You can get SΦ(f) as "1*Phase Noise" in "pnoise jitter of Direct Plot Form". |
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Title: Re: True Sphi Plot in Cadence ? Post by Mayank on Dec 11th, 2009, 1:38am hi Pancho, That's what you indicated in one of your earlier posts also....But when i simulate it, both pnoise jitter & LLSB from pnoise modulated options give same phase noise plots -- exactly equal... Also, Is there a way to convert Output Noise SV(f) into true SΦ(f) -- I could try this if you could suggest me how ?? Also, what is the correspondence between the units dBrad/Hz & dBc/Hz ?? -- As in i mean, if i know that phase noise of -40dBc/Hz @ 10kHz offset, how do i know it's equivalent in SΦ(f) ?? thanx, mayank. |
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Title: Re: True Sphi Plot in Cadence ? Post by pancho_hideboo on Dec 11th, 2009, 1:42am I think you should post your questions in http://www.cadence.com/Community/forums/33.aspx not in this forum. Mayank wrote on Dec 11th, 2009, 1:38am:
Phase Noise in "pnoise=jitter of Direct Plot Form" is about 3dB larger value than LUSB(f) of "pnoise=sources". I don't know why your results of them are completely same. Your results in http://www.designers-guide.org/Forum/YaBB.pl?num=1050465395/17#17 are coincident with my results. Mayank wrote on Dec 11th, 2009, 1:38am:
But LUSB(f) of "pnoise=sources" is not true normalized SV(f). I don't think I can get true normalized SV(f) by using Cadence Spectre. Mayank wrote on Dec 11th, 2009, 1:38am:
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Title: Re: True Sphi Plot in Cadence ? Post by Mayank on Dec 11th, 2009, 2:14am Hi Pancho, I will check my simulation once again for pnoise jitter & pnoise sources.... As for true Sphi, are there any other simulators like Agilent ADS / GoldenGate / synopsis XA / eldo / bdasim - which can provide true Sphi instead of LSSB/LUSB/LLSB ?? I can try some other simulator. regards, mayank. |
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Title: Re: True Sphi Plot in Cadence ? Post by pancho_hideboo on Dec 11th, 2009, 2:18am Mayank wrote on Dec 11th, 2009, 2:14am:
As far as we use small signal noise analysis in frequency domain, we can never get true result. This is true for any vendor's simulators. http://www.designers-guide.org/Forum/YaBB.pl?num=1259714206/2#2 |
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