( ESNUG 311 Item 12 ) --------------------------------------------- [2/18/99]
Subject: ( ESNUG 310 #15 ) Is Modeling Load-Dependent Pins An Afterthought ?
> Anyone, anywhere, could you please share any experience you have modeling
> load-dependent cell library pins.
>
> The 98.08 manuals devote a whopping 3 pages to this topic in what looks
> like an afterthought, not a real feature. I say this because load
> dependent timing appears to be supported *only* for constraint arcs, not
> delay or combinational arcs. Why in the world would that be so?
>
> - Andy Pagones
> Motorola Chicago Corporate Research Laboratories
From: [ A Synopsys Field Engineer ]
John,
Andy is correct. Load-dependent timing is not available for delay or
combinational arcs. The reason for not having them previously was that
there were no vendors asking for that level of accuracy with their
libraries. With the advent of some of the new, smaller geometries, vendors
are requesting the increased accuracy, so they are being added this year.
On the technical side, the real reason that Load-dependent delays are not
available is that they require a 3-Dimensional lookup table, which has
not been supported previously. It will be part of the release coming out
around August.
- [ A Synopsys Field Engineer ]
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