Subject: SSO answer to Greg's question

From: [email-masked]
Date: Tue, 28 Feb 1995 19:59:33 -0800

>To: [email-masked]
>From: [email-masked] (Greg Edlund)
>Subject: Does IBIS cover SSO noise?
>Content-Length: 787
>X-UIDL: 794017938.004
>
>I've begun taking a look at IBIS modeling and what it
>has to offer for us, and the one thing that sticks out
>to me is that I don't see any provisions for simultaneously
>switching output (SSO) noise.  This can be a big part of
>your noise budget, especially when you're pressed for
>chip-to-chip timing and there's no logic between the
>latch and the driver.  Does anybody know if SSO capability
>exists within IBIS?  If it does not, are there plans to
>incorportate it?
>
Hi Greg, Yes IBIS can handle SSO.  It is more a question of what the simulators
do with the data.  The IBIS models include package information about ground
inductance, VCC inductance etc.  Additionally Ver 2.x of IBIS adds the
ability to define which power supply pins go with each of the output pins.  This
was the piece that was missing to provide good SSO simulation.  Now the next
part of your question really is do any of the simulator vendors use this data.
And that needs to be answered by each vendor separately.  It may also require
that you as a user get involved and specify how many outputs and which outputs
you want to simutaneously transition.  Is it all 8 outputs on an octal or
just 2.

Kellee Crisafulli, HyperLynx Inc.

Have a great day...