Subject: General questions

From: [email-masked] (Syed Huq)
Date: Wed, 14 Dec 94 10:30:43 PST

Hello IBISgurus:

I have been talking about IBIS to different groups at National and
some questions regarding IBIS's capability came up.

Can IBIS model an output stage with 'gradual turn-on' feature ?
For example, products like LV TTL have gradual turn-on ckts on the
output stage so if an Octal were to switch, GND bounce would be reduced. 
I would like to know if anyone has modeled this using IBIS.

The other question is, some product line(ex. GTL) have a feedback path
from output to input. Is there any limitations with IBIS modeling this
type of structure.

My feeling is, 'gradual turn-on' or 'feedback' are very device specific
features and IBIS simply sees the I/O structure and all else is a black 
box within the device.

I would be curious if anyone is modeling LV TTL or GTL type of devices.

Comments...questions..

Regards,
Syed.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Syed B. Huq 
Applications Engineer/Data Transmission Products
National Semiconductor 
Tel:(408)721-4874; Fax:(408)721-4785
Internet:[email-masked]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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From: [email-masked] (Jon Powell)
Date: Wed, 14 Dec 94 12:57:12 PST

Syed,

I believe that the waveform mechanism can handle many forms of the "gradual turn on" and
the "feed back" drivers. In fact, I believe that is what INTEL wanted to use these
waveforms for in the first place (so called Rise Time Controlled drivers).

The feed back issue is harder since it depends on the speed of the feedback mechanism and that
speed is NOT defined (as yet) in the IBIS format.

jonp