( ESNUG 335 Item 2 ) ---------------------------------------------- [11/3/99]
From: Andrew Pagones <Andy_Pagones-ACIC22@email.mot.com>
Subject: Does Anyone Actually Use 3-Dimensional (Load-Dependent) Timing?
Hi, John,
I'd like to rehash an old issue now that it's possible to actually use it.
Synopsys version 1999.10 supports 3-dimensional lookup tables for delay
modeling. I hope to find out what other tools (e.g., Avanti, Cadence, etc.)
already have or plan to have compatible timing modeling. What have you
heard from your vendors? Are there characterization tools out there that
can write .lib's with this syntax?
Also, the Synopsys docs note that 3D modeling is useful for cells with
load-dependent outputs, such as unbuffered flops or adders. My local
Synopsys rep, however, related a customer complaint that even buffered
outputs exhibit a slight degree of dependence on the other output's
loading and that the inaccuracies increase with finer geometry processing.
I'd like to ask the ESNUG readers to please share their experiences with
this issue and enlighten us.
- Andy Pagones
Motorola Labs
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