Subject: Re: Bird38

From: [email-masked] ( Bob Ross)
Date: Thu, 5 Sep 96 13:01 PDT

John and Ahmed:

We have all had a "vacation" from IBIS committee discussions and 
need to get restarted in our discussions.  I do not have answers
to your questions, but this will be subject for discussion at the
Friday Meeting.  Along with Egg12, Ahmed Omera also submitted
a dynamic noise proposal a long while ago which also in in the
Specification enhancement category.

Jon Powell had proposed a Specification sub-committee to consider
all proposals together, but we have not acted on this yet.

My preference is that any enhancement be simple.  While some of the
proposals involve tables, I suspect that the practical reality is
that (1) there is too much data for anyone to really specify, and
(2) very few vendors will consider processing that specific 
enhancement.  Also, I favor consistency with the existing conventions
and structure rather than adding very specific, special purpose,"warts".
By this, any extension needs to work with all of the technologies and
be meaningful for all of the columns.

Anyway, this is what we can consider on Friday.

Bob Ross,
Interconnectix, Inc.

> To: [email-masked]
> Subject: Bird38

> Hello all,

> Since proposing bird 38, I have received little comment. As I was not
> able to attend the last two meetings, this is probably my fault.

> This bird is closely associated with egg12 i.e. it is a 
> specification addition.

> Bird38 is basically a way to specify under- and overshoot limits.

> A simplification of this bird would be to just give two numbers,
> max_undershoot and max_overshoot. This is what a lot of simulators
> do, and there is a place to stick these numbers into a RAIL file.

> But in this case, over what time span is the over/undershoot allowed
> to be present. I have read through the RAIL doc, but cannot  find an
> answer to this question.

> What do people out there understand by over/undershoot limits, as
> used in present simulators?

> All feedback appreciated.
>  
> Cheers,
> John

>  
> -- 
> John Fitzpatrick   <[email-masked]>    
> Alcatel CIT, 4 rue de Broglie, 22304 Lannion, France
> Tel: (+33)96.04.79.33  Fax: (+33)96.04.85.09

---

From: FITZPATRICK John <[email-masked]>
Date: Fri, 06 Sep 1996 13:45:37 +0200

Bob,

I agree that any specification enhancement should be simple and
consistent. 

A very simplified version of bird 38, which would satisfy most
needs would give an entries similar to the following:

example a:
[Over/undershoot]
|Time   Max_overshoot   Max_undershoot
 0         0.5            -0.5 

example b:

[Over/undershoot]
|Time   Max_overshoot   Max_undershoot
 20ns      2.0             -2.0
 20.1ns    0.5              0.5

Example a) would cover the case where the dynamic and static overshoots
and undershoots are the same as the dynamic values.

Example b) shows much more realistic and useful values. The 
dynamic overshoot is 2.0V above Vcc. This is the value that might
be transferred into a RAIL file.

I'm not familiar enough with IBIS to understand what you mean by:
 - "existing conventions" (what is wrong with tables?)
 - "technologies" (simulator technology or semiconductor technology?)
 - "meaningful for all columns" 

Talk to you later,
John

Bob said: 
> enhancement.  
> Also, I favor consistency with the existing conventions