RE: [IBIS-Users] IBIS File Help

From: Tom Dagostino <tom@teraspeed.com>
Date: Fri Feb 05 2010 - 15:00:55 PST

Eric

I'm not sure you are describing your problem fully here so that others can
help you.

Most of the ECL drivers I have seen are open emitter drivers not open
collector. A few I have seen emulate the ECL levels using more conventional
topologies but limit the swing of the output to ECL levels. I am unfamiliar
with ECL levels that are supposed to swing to what I assume is your supply
rail of 3.3V. Most ECL is terminated with a 50 Ohm load to Vcc - 2V or 1.3V
for the case of Vcc = 3.3V. And the voltage swing is on the order of 0.9V.

If you could be more specific about your circuit, supply voltages, output
termination resistance and voltage we may be able to help.

Regards,

Tom Dagostino
Teraspeed(R) Labs
13610 SW Harness Lane
Beaverton, OR 97008
503-430-1065
503-430-1285 FAX
tom@teraspeed.com
www.teraspeed.com

Teraspeed Consulting Group LLC
121 North River Drive
Narragansett, RI 02882
401-284-1827

-----Original Message-----
From: owner-ibis-users@eda.org [mailto:owner-ibis-users@eda.org] On Behalf
Of Eric Monteiro
Sent: Thursday, February 04, 2010 10:22 AM
To: ibis-users@eda.org
Subject: [IBIS-Users] IBIS File Help

Hello

I have generated an IBIS file for an ECL open collector driver. When I do
the IBISCKH, I get 0 warnings and 0 errors. However, when I try to use the
model in a certain tool, the output swings are not as expected.

1) My [Rising Waveform] and [Falling Waveform] shows the wave go from 1.7 to
3.3 volts.
2) IBIS CHK comes back clean, so my DC tables must agree that those are the
end points.
3) I place the part into the tool, terminate the open collector to the same
R_fixture and V_fixture in the IBIS file
4) I run at the correct data rate, and the output comes out at 1.7 to 2.2
volts...

However in a different simulator I get 1.7 to 3.3 with the same test
bench... BUT if I delete the [Rising Waveform] and [Falling Waveform] data,
the two simulators agree.

Has anyone seen this with thier models?

Does this mean there is an issue with my IBIS files DC data? I am quite
puzzled on this one.

(The file is quite large, I can send it to anyone interested in this issue)

Best Regards,
Eric

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Received on Fri Feb 5 15:06:14 2010

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