Subject: Bird 17, 101 points in tables

From: [email-masked] (Will Hobbs)
Date: Wed, 20 Jul 94 13:54:36 -0700

Hello IBIS members:

This BIRD extends the number of points from 100 to 101 per last IBIS Forum 
discussion.  Upon further reflection, the proposed number of points for the 
[Pullup] and [Pulldown] tables is increased to 151 since they are mandated 
to extend of larger voltage ranges.  The primary reason for these extensions 
is to allow automated IBIS file creation programs to sweep over the entire 
voltage data range of -5V to 10V at .1V increments, capture the endpoints 
and the 0V and 5V points.

Scott Bloom, Interconnectix, Inc.

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                 Buffer Issue Resolution Document  (BIRD)

BIRD ID#:                17
ISSUE TITLE:             Number of Points
REQUESTOR:               Scott Bloom, Interconnectix, Inc. 
DATE SUBMITTED:          17 July 1994
DATE REVISED:
DATE ACCEPTED BY IBIS OPEN FORUM:     Pending

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STATEMENT OF THE ISSUE:

The limits on the number of points for the [Pullup] and [Pulldown] keywords 
is increased from 100 to 151 to allow automated and simulated capture routines
to sweep from -5V to +10V at .1V increments.  Similarly the number of points 
for [GND clamp] and [POWER clamp] tables is increased from 100 to 101, again 
allowing .1V increments for the [GND clamp] table from -5V to 5V.  Also the
the number of points for [Rising Waveform] and [Falling Waveform] tables 
is increased from 100 to 101 to allow, for example, time sweeps from 0 to 10ns
at .1ns increments.

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STATEMENT OF THE RESOLVED SPECIFICATIONS:

For the keywords [Pulldown], [Pullup], [GND Clamp], and [POWER Clamp], under 
Usage Rules, the last sentence of the second paragraph is changed into two 
sentences.  The second paragraph becomes:

|               All four columns are required under these keywords.  However, 
|               data is only required in the typical column.  If minimum
|               and/or maximum current values are not available, the reserved 
|               word "NA" must be used.  "NA" can be used for currents in the 
|               typical column, but numeric values MUST be specified for the 
|               first and last voltage points on any V/I curve. Each [Pullup]
|               and [Pulldown] V/I curve must have at least 2, but not more
|               than 151, voltage points.  Each [GND Clamp] and [POWER Clamp] 
|               V/I curve must have at least 2, but not more than 101, voltage
|               points.

For the keywords [Rising Waveform] and [Falling Waveform], the second to last 
sentence of the first paragraph of Usage Rules is changed:  It now becomes:

|     Usage Rules:  Each [Rising Waveform] and [Falling Waveform] keyword 
|                   introduces a table of time vs. voltage points that
|                   describe the shape of an output waveform.  These
|                   time/voltage points are taken under the conditions 
|                   specified in the R/L/C/V_fixture and R/L/C_dut
|                   sub-parameters.  The table itself consists of
|                   one column of time points, then three columns of
|                   voltage points in the standard typ, min, and max format. 
|                   The four entries must be placed on a single line and
|                   must be separated by at least one white space or tab
|                   character.  All four columns are required.  However, data 
|                   is only required in the typical column.  If minimum
|                   or maximum data is not available, use the reserved word 
|                   "NA".  The first value in the time column need not be '0'.
|                   Time values must increase as one parses down the table. 
|                   The waveform table can contain a maximum of 101 data
|                   points.  A maximum of 100 waveform tables are allowed per 
|                   model.  Note that for backwards compatibility, the existing
|                   [Ramp] keyword is still required. 
|

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ANALYSIS PATH/DATA THAT LED TO SPECIFICATION

Automated generation of IBIS file VI and time tables typically can be done 
with linear voltage and linear time sweeps over the entire required range. 
A typical range for CMOS and TTL devices with Vcc = 5V is from -5V to 10V 
at .1V increments.  This would require 151 points for the [Pullup] and 
[Pulldown] tables.  Similarly, the [GND Clamp] tables would be tabulated 
from -5V to 5V at .1V increments, requiring 101 points.  The [Rising 
Waveform] and [Falling Waveform] could be presented with some utilities at 
constant time increments.  In order to capture a typical range such as
0 to 10ns at .1ns increments, 101 points would be needed.

Even though there may be unnecessary points, this proposal increases the 
limits in a proportional manner.  It allows typical ranges that align the V/I 
tables to be presented without requiring any further processing.

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ANY OTHER BACKGROUND INFORMATION

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From: Arpad Muranyi <[email-masked]>
Date: Tue, 26 Jul 94 08:48:09 PST

Text item: Text Item

Jon,

I guess we are back to the good old question again:  do we provide data as it 
comes off of the measurements, or do we make it easier for the tool to use it.
In other words, should the person making the measurements extract the best 100 
points or the (SPICE) tool vendor in the software.

It seems to me that you like the beef as red as possible (raw data) which is 
good for those making the measurements.  I am just wondering, do all the (SPICE)
vendors subscribe to this?

Arpad Muranyi
Intel Corporation

Subject: Bird 17, 101 points in tables 

About SPICE limitations etc:
I don't really care if we allow more than 100 points but I don't think that
SPICE (or any other simulator) limitations should be a consideration when making

IBIS rules. If data wants to be in a certain format we should let it be that way
and let the simulator companies force it into the proper format.
I bet that if the SPICE companies got 200 point arrays they would figure out
a way to get 100 good points out of it.

jonp