FreeLists / si-list / [SI-LIST] Re: Co-Relation between Mentor Graphics ICX SI measurements & Actual SI Measurements

["Lynne Green" <lgreen22@xxxxxxxxxxxxxx>]

Tony is right that great care is required for testing as well as for PCB and
SPICE/IBIS modeling and simulation.

So one more caveat - in some cases, the simulation won't match the
measurement unless the simulation includes the parasitics of the test probe.

- Lynne

Lynne Green 
Greenstreak Programs

-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On
Behalf Of Dunbar, Tony
Sent: Thursday, April 01, 2004 7:03 AM
To: 'si-list@xxxxxxxxxxxxx'
Subject: [SI-LIST] Re: Co-Relation between Mentor Graphics ICX SI
measurements & Actual SI Measurements

I concur with Giancarlo's opinion about the two important simulation
accuracy factors he references, but would also like to add that the accuracy
of a measurement can only be as good as simulation when care is taken to use
suitable measurement hardware and measure at the correct points. This not
aimed directly at Giancarlo - but at other people's comments in this thread
and similar, previous threads - it's always interesting to see that
simulation seems to be postulated as the inferior, fraught-with-danger
method when I have come across so many cases when engineers report that when
they, for example, used a different probe or changed something else in their
lab setup, the measurement then 'matched' the simulation. Either method can
be employed shoddily or carefully and knowledgeably, with consequent
results.

Tony

-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx
[mailto:si-list-bounce@xxxxxxxxxxxxx]On Behalf Of Giancarlo Guida
Sent: Thursday, April 01, 2004 12:10 AM
To: shiraz_bashir@xxxxxxxxx; si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Re: Co-Relation between Mentor Graphics ICX SI
measurements & Actual SI Measurements


Hi
in my opinion
the accuracy of an SI simulation strongly depends
on 2 factors:
1) quality of I/O buffer models
2) extraction of the model for the Pcb signals

For the second factor you should consider that
if the exctraction you are using  is  based  only on 2D alghorithm then
it could be not such accurate at least in some cases

As you said due to the complexity of the board
and the increase speed often a 3D approach is a must ...

I performed simulation based on mixed 3D/2D approach
and the comparison between measurement and simulation
is really good

Simulation is not going to substitue measurement
but if used during design can allow to obtain high quality product
saving time and effort.

Giancarlo

----- Original Message -----
From: "Shiraz Bashir" <shiraz_bashir@xxxxxxxxx>
To: <si-list@xxxxxxxxxxxxx>
Sent: Thursday, April 01, 2004 7:22 AM
Subject: [SI-LIST] Co-Relation between Mentor Graphics ICX SI measurements &
Actual SI Measurements


All,

Would me body please tell me that is there any
co-relation between Mentor Graphic's ICX SI
measurements and actual SI measurements ?

Can we rely solely on IBIS models provided by
manufacturers to 'acuratley' predict SI measurements ?
Or one has to 'improve' the IBIS models ?

With today's time to market pressures, complexity of
circuit boards, does one can rely on Mentor Graphic's
ICX tool to predict SI problems so that one can reduce
the actual SI measurements on board ?

thanks in advance for your time and help.

shiraz bashir



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