Subject: [IBIS-Users] SSO effect
From: Yaping Zhou (y.zhou@motorola.com)
Date: Mon Apr 15 2002 - 11:07:29 PDT
Hi, all:
This is an excerption from IBIS Cookbook. I have one question about it, and
need your help.
"Inclusion of SSO Effects
Closely related to the discussion on model limits is the decision on how to
include Simultaneous Switching Output (SSO) effects. SSO effects can be
included explicitly in a model by measuring the I/V and edge rate
characteristics under SSO conditions. For example, a buffers I/V
characteristic can be measured with all the adjacent buffers turned on and
sinking current, or the buffers edge rate may be measured while adjacent
buffers are also switching. Alternatively, a model that represents a single
buffer in isolation may be created, then several buffers may be connected to
a common power or ground rail via the [Pin Mapping] keyword. The former
method (including SSO effects in the models' I/V and edge rate tables) has
the advantage that the resulting model is straight forward to verify and
less dependent on any particular simulators capability. Note however, the
[Pin Mapping] keyword method does give the user the ability to perform
explicit ground bounce simulations and devise specific 'what if' scenarios.
"
When [Pin Mapping] is used, do we still need to measure V-I under SSO
condition? I think we should because we need to know how buffers respond
when voltage droop happens due to simultanuous switching.
Thanks in advance.
Yaping Zhou
Motorola Inc.
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