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Frank Wiedmann

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Re: Phase Noise of ECL Level Divider
Reply #15 - Oct 02^nd, 2006, 1:57am

Ken, just to be clear: I absolutely agree with everything you wrote. As far as I can tell, both the normal and the timedomain/strobed pnoise analyses work absolutely correctly for both driven and autonomous circuits. What I am arguing against is the way the pnoise jitter analysis (which is a relatively new and separate analysis type) is currently implemented for the autonomous case. I do not think that this way is very useful and it would have been much better to implement the pnoise jitter analysis for autonomous circuits in just the same way as for driven circuits.

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Ken Kundert Global Moderator Offline Posts: 2384 Silicon Valley	Re: Phase Noise of ECL Level Divider Reply #16 - Oct 2^nd, 2006, 8:22am I understand. I have not seen this newer version yet, but I'll make sure that Cadence reads this thread. -Ken
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Vick

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Re: Phase Noise of ECL Level Divider
Reply #17 - Oct 6^th, 2006, 6:04am

[quote author=timmc6 link=1158788102/0#0 date=1158788102]Hello,

Also, I am not sure if I should use an 'absolute' sweep or 'relative' sweep in PNOISE. �

Hy! I'm still waiting for an answer to this question, relative or absolute? It seems to me that an Absolute Sweeptype is equivalent to a Relative one with Relative Harmonic parameter set to 0. And I think that this is the correct way of predicting the noise near the main output frequency (Is that so?). Then why some people suggests as the correct Relative Harmonic = 1 in the pnoise form of Spectre?
Thanks.

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Vick

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Ken Kundert Global Moderator Offline Posts: 2384 Silicon Valley	Re: Phase Noise of ECL Level Divider Reply #18 - Oct 6^th, 2006, 10:17am If you are using strobing, it does not matter as the noise is periodic in frequency. -Ken
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neoflash Community Fellow Offline Mixed-Signal Designer Posts: 397	Re: Phase Noise of ECL Level Divider Reply #19 - Jul 5^th, 2011, 10:54am Ken, When you mention strobed analysis, you mean noisetype = "time-domain" or "jitter" ? Ken Kundert wrote on Oct 6^th, 2006, 10:17am: If you are using strobing, it does not matter as the noise is periodic in frequency. -Ken
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Ken Kundert Global Moderator Offline Posts: 2384 Silicon Valley	Re: Phase Noise of ECL Level Divider Reply #20 - Jul 5^th, 2011, 10:31pm Yes.
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neoflash Community Fellow Offline Mixed-Signal Designer Posts: 397	Re: Phase Noise of ECL Level Divider Reply #21 - Jul 5^th, 2011, 10:35pm Ken, It is actually a selective question. noisetype = "time domain" or "jitter".
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Frank Wiedmann

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Re: Phase Noise of ECL Level Divider
Reply #22 - Jul 6^th, 2011, 12:52am

For pnoise analysis, the timedomain and jitter noisetypes (PM jitter for autonomous circuits) are almost identical. The only difference is how you specify the strobing times. In general, noisetype=pmjitter is more useful because you specify the times by using threshold crossings. The noisetype=timedomain is the older variant, there you specify the times with respect to the result of the pss analysis.

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neoflash

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Re: Phase Noise of ECL Level Divider
Reply #23 - Jul 6^th, 2011, 11:02am

Thanks for the comments.

I'm surprised that Cadence's documentation is so weak on this topic. And users have to go beyond their website to understand this basic usage information.

At least, they should provide application notes for VCO, driven circuits and PFD/CP. The step by step setup procedures and result processing.

Frank Wiedmann wrote on Jul 6^th, 2011, 12:52am:

For pnoise analysis, the timedomain and jitter noisetypes (PM jitter for autonomous circuits) are almost identical. The only difference is how you specify the strobing times. In general, noisetype=pmjitter is more useful because you specify the times by using threshold crossings. The noisetype=timedomain is the older variant, there you specify the times with respect to the result of the pss analysis.

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neoflash Community Fellow Offline Mixed-Signal Designer Posts: 397	Re: Phase Noise of ECL Level Divider Reply #24 - Jul 6^th, 2011, 11:25am Removed wrong question.
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neoflash

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Re: Phase Noise of ECL Level Divider
Reply #25 - Jul 6^th, 2011, 12:01pm

When I was trying to convert the Jee (Sec/Hz) in "PM jitter" mode to phase noise in "source" mode, I found they are nicely offset by 112dBc.

I was using below equation for this conversion:

multiple Jee with term "sqrt( 2*pai*Fo )" and do 20*log10() to get the expected phase noise curve.

However, the calculated from Jee is 112dB lower than phase noise from source mode. I'm not sure which step go wrong.

- Neo

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Frank Wiedmann Community Fellow Offline Posts: 677 Munich, Germany	Re: Phase Noise of ECL Level Divider Reply #26 - Jul 6^th, 2011, 3:03pm Have you carefully read the thread at http://www.designers-guide.org/Forum/YaBB.pl?num=1224609785 ? You will probably find the answers to most of your questions there.
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neoflash Community Fellow Offline Mixed-Signal Designer Posts: 397	Re: Phase Noise of ECL Level Divider Reply #27 - Jul 6^th, 2011, 4:25pm Oops. Correct equation but one term square rooted by mistake. It turns out that Jee converted will be DSB while source mode is SSB. Jee is 3dB higher. I think Cadence should follow the same guideline for DSB and SSB for all modes.
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