[SI-LIST] Re: Measurement/Simulation Correlation
- From: "Yuriy Shlepnev" <shlepnev@xxxxxxxxxxxxx>
- To: <Ravinder.Ajmani@xxxxxxxx>, <si-list@xxxxxxxxxxxxx>
- Date: Sun, 10 Jun 2012 12:24:56 -0700
Hi Ravinder,
You have got some good advices already and I just wanted to elaborate a
little on the validation of analysis with measurements (or the other way
around).
I have participated in a number of such projects with our partners and our
experience and the results were reported and published at DesignCon every
year since 2009 (papers and presentations are available at
http://www.simberian.com/AppNotes.php - #2009_03, 2010_01, 2011_02, 2011_03,
2012_01).
You have to develop a systematic approach to identify the limits of your
tool on a set of structures typically used in your design.
It obviously must start with the broadband dielectric and conductor
roughness model parameters identification.
Without such models any analysis is useless and you may end up with
"tweaking" the material parameters to match the data. Worst case scenario is
"tweaking" the parameters for every structure on the board if some physical
effects are not included in the models (even geometry is "tweaked" some
time).
With the appropriate material parameters identification (with two line
segments and GMS-parameters for instance), the analysis of typical
structures on the board should correlate well with the measurements without
any additional adjustment of the material model parameters. Deviation of
measured data from simulated indicates either at the limits of the model, or
geometrical difference of a model and actual board. If your vias for
instance cannot be simulated in isolation from the rest of the board (not
localizable), the analysis will always deviate from the measurements even
with 3D electromagnetic modeling. The geometrical differences is the last
resort if the discrepancies cannot be explained otherwise - the board may
need cross-sectional investigation (you may find some surprises from you
manufacturer). With a systematic approach in place and couple of iterations
you will have a board with behavior that can be reliably predicted with your
existing or newly selected tools.
Note that the measurements may also need the validation, especially if
de-embedding is involved.
If you are not confident both in analysis and measurements, I would
recommend you to get a board that was previously measured and simulated up
to your target frequency - something like CMP-08 from Wild River Technology
(http://wildrivertech.com/) featured in multiple DesignCon papers.
Best regards,
Yuriy
Yuriy Shlepnev, Ph.D.
President, Simberian Inc.
3030 S Torrey Pines Dr. Las Vegas, NV 89146, USA
Office +1-702-876-2882
Cell +1-206-409-2368
Skype: shlepnev
www.simberian.com
-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On
Behalf Of Ravinder.Ajmani@xxxxxxxx
Sent: Friday, June 08, 2012 3:59 PM
To: si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Measurement/Simulation Correlation
Hi Experts,
I have built a simple test board for correlating the simulated S-Parameter
data (extracted using Ansoft SIwave) with VNA measurements. I get good
Insertion Loss correlation up to 12 GHz, buy beyond that the measured
Insertion Loss drops more significantly than the simulated data. I have
tried tweaking the dielectric loss, but it does not help much. Could this
added loss be due to surface roughness, which I have not taken in to
account, or the tool limitation. I do get better correlation with the
Mixed-Mode Insertion Loss (within 2 dB up to 20 GHz).
I may add that my colleague generated S-parameter data on the same design
using Agilent Momentum, which correlates well up to 16 GHz, but also shows
resonances that don't show up in the measurements. It also correlates well
with Mixed-Mode Insertion Loss.
I will appreciate any lead in to this.
Thanks.
Regards
Ravinder Ajmani
HGST, a Western Digital company
ravinder.ajmani@xxxxxxxx
------------------------------------------------------------------
To unsubscribe from si-list:
si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field
or to administer your membership from a web page, go to:
//www.freelists.org/webpage/si-list
For help:
si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field
List forum is accessible at:
http://tech.groups.yahoo.com/group/si-list
List archives are viewable at:
//www.freelists.org/archives/si-list
Old (prior to June 6, 2001) list archives are viewable at:
http://www.qsl.net/wb6tpu
------------------------------------------------------------------
To unsubscribe from si-list:
si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field
or to administer your membership from a web page, go to:
//www.freelists.org/webpage/si-list
For help:
si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field
List forum is accessible at:
http://tech.groups.yahoo.com/group/si-list
List archives are viewable at:
//www.freelists.org/archives/si-list
Old (prior to June 6, 2001) list archives are viewable at:
http://www.qsl.net/wb6tpu
Other related posts:
