RE: [IBIS-Users] Ramp Rate


Subject: RE: [IBIS-Users] Ramp Rate
From: Tom Dagostino (tom@teraspeed.com)
Date: Thu Dec 26 2002 - 10:56:19 PST


Most output buffers have many stages between the point that you stimulate it
and the output node that you are measuring. Each of these stages have some
gain. The gain plus the number of stages involved will take a slow input
ramp and normalize it so that what you see is the same slew rate in the
output for any reasonable input ramp. You will likely see a different time
delay through the buffer based on the slew rate of the input but the output
slew rate will remain constant.

Tom Dagostino
Teraspeed Consulting Group LLC Teraspeed Consulting Group LLC
2926 SE Yamhill St. Device Modeling Division
Portland, OR 97214 13610 SW Harness Lane
                                   Beaverton, OR 97008
http://www.teraspeed.com 503-430-1065
tom@teraspeed.com

-----Original Message-----
From: owner-ibis-users@server.eda.org
[mailto:owner-ibis-users@server.eda.org]On Behalf Of Anshuli Goel
Sent: Thursday, December 26, 2002 4:27 AM
To: ibis-users@eda.org
Subject: [IBIS-Users] Ramp Rate

Hello IBIS Gurus

I am trying to generate the IBIS model of a Bi-di buffer in only output
direction. In first case in s2ibis2 script I give 1ns as rise and fall
time and in the output IBIs file I get some ramp rate,
     in second case I change the rise and fall time in s2ibis2 script
but in the output IBIS file the ramp rate is not changed as compared to
first case.
( While I expected it to change since output rise and fall time depends
on input slew and output load , in this case only input slew is changing
) .

Why this is happening ?
Is there some other parameters also that I need to change ?

Regards
Anshuli

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