[ibis-macro] Re: Statistical vs. Time Domain BER Predictions?
- From: "Muranyi, Arpad" <Arpad_Muranyi@xxxxxxxxxx>
- To: 'IBIS-ATM' <ibis-macro@xxxxxxxxxxxxx>
- Date: Fri, 16 Mar 2012 05:30:35 +0000
Todd,
My point was not that things cannot be approximated. My
point was that there was more than just Jitter in the
answer to Dave's question. My DFE example was just one
of the many, to which you added a few more.
The bottom line is that this kind of comparison is kind
of like comparing apples and oranges, i.e. the answer
"depends" as you said it...
Thanks,
Arpad
==========================================================
From: ibis-macro-bounce@xxxxxxxxxxxxx [mailto:ibis-macro-bounce@xxxxxxxxxxxxx]
On Behalf Of Todd Westerhoff
Sent: Thursday, March 15, 2012 9:38 PM
To: 'IBIS-ATM'
Subject: [ibis-macro] Re: Statistical vs. Time Domain BER Predictions?
Arpad,
Statistical simulations using AMI_Init can do a good job of approximating DFE
behavior, even though they're not simulating the bit by bit adaptive behavior
of DFE algorithms.
Mike Steinberger provided a good overview of the approach here:
http://www.eeweb.com/blog/michael_steinberger/what-bumblebees-and-models-of-dfe-have-in-common
David,
The answer to your original question is (as it so often is) - "it depends".
Statistical algorithms tend to simulate random, unencoded data ... so, if your
time-domain simulation uses 8B10B encoding, that can cause results to vary
significantly (32B33B and 64B66B have much smaller effects). Another
significant factor is the length of the time-domain simulation, which goes to
probability depth. Statistical simulations, by their very nature, can compute
probabilities beyond 1E-30. Time domain simulations tend to be 1E7 bits or
less, so accurately predicting statistics down to levels we care about (1E12
and less) gets trickier.
Hope that helps,
Todd.
Todd Westerhoff
VP, Software Products
Signal Integrity Software Inc. * www.sisoft.com<http://www.sisoft.com/>
6 Clock Tower Place * Suite 250 * Maynard, MA 01754
(978) 461-0449 x24 * twesterh@xxxxxxxxxx<mailto:twesterh@xxxxxxxxxx>
"Three in the morning and I'm still awake,
So I picked up a pen and a page ... "
-Sidewalk Prophets
From: ibis-macro-bounce@xxxxxxxxxxxxx<mailto:ibis-macro-bounce@xxxxxxxxxxxxx>
[mailto:ibis-macro-bounce@xxxxxxxxxxxxx]<mailto:[mailto:ibis-macro-bounce@xxxxxxxxxxxxx]>
On Behalf Of Muranyi, Arpad
Sent: Thursday, March 15, 2012 7:28 PM
To: 'IBIS-ATM'
Subject: [ibis-macro] Re: Statistical vs. Time Domain BER Predictions?
David,
There is more to it than RMS jitter.
In TD simulations you can include the non-linear DFE
algorithms, for example, which is simply omitted in
Statistical analysis. It's comparing apples and
oranges...
Thanks,
Arpad
==============================================================
From: ibis-macro-bounce@xxxxxxxxxxxxx<mailto:ibis-macro-bounce@xxxxxxxxxxxxx>
[mailto:ibis-macro-bounce@xxxxxxxxxxxxx]<mailto:[mailto:ibis-macro-bounce@xxxxxxxxxxxxx]>
On Behalf Of David Banas
Sent: Thursday, March 15, 2012 6:08 PM
To: 'IBIS-ATM'
Subject: [ibis-macro] Statistical vs. Time Domain BER Predictions?
Hi Experts,
When comparing the BER estimates of the Statistical and Time Domain operating
modes of an EDA tool, would you expect:
1) Statistical to estimate lower or higher BER than time domain?
2) Expect the differences between the 2 modes to go to zero, as the
difference between their estimates of RMS jitter goes to zero? (Said another
way, perhaps: are BER extrapolation errors mainly due to errors in RMS jitter
estimation?)
Thanks!
David Banas
Sr. Member Technical Staff
Altera<http://www.altera.com/>
+1-408-544-7667 - desk
Did you know Altera offers over 150 free online technical training
courses<http://www.altera.com/servlets/searchcourse?coursetype=Online&WT.mc_id=t9_ot_mi_mi_tx_a_311>?
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