[ibis-quality] IQ_4_4_ramp_data.txt

From: "Mike LaBonte" <milabont@xxxxxxxxx>
To: <ibis-quality@xxxxxxxxxxxxx>
Date: Thu, 12 Jun 2003 14:58:36 -0400
Here is the ramp data document with updates from the 10jun2003 call.
This will also be posted at http://www.sisoft.com/ibis-quality

Mike

FILENAME: IQ_4_4_ramp_data.txt
Rev 0.1  05/27/2003 Split off in text format from ramp_waveproc.doc.
                    Updated from 5/20/2003 review.
Rev 0.2  06/12/2003 ML - Add ibischk3 info
                    Updated from 6/10/2003 review.

Section 4.4 Ramp Data

The [Ramp] section is required even if Rising_waveform and
Falling_waveform are present in a [Model]. Ramp information is used in
some tools for non-simulation purposes, for example quickly finding the
fastest pin on a net.

1. All buffers capable of output have a Ramp section.  Input-only buffers,
   terminators, Series and Series_switch models do not have a Ramp section.
   (level 0) (ibischk 3.2.9+)

2. If the Ramp data was measured using a load resistor other than 50 ohms,
   the Ramp section has an R_load subparameter giving the load resistor
value
   used.
   (level 1)

3. The fixture used for generating Ramp measurement waveforms has only the
   buffer, a load resistor, and a terminating voltage. No capacitors or
   inductors, for example.
   (level 1)

4. The typ, min, and max Ramp values are taken from typ, min, and max
   buffer measurements. They are not necessarily sorted by dV, dt, or dV/dt.
   (level 1)

5. The dV and dt values are greater than zero. Note that s2ibis2 will
   incorrectly generate negative Ramp values in the case where the Ramp
   simulation duration is much longer than the Ramp dt, leaving no waveform
   points that fall between the 20% and 80% voltage levels.
   (level 0) (ibischk 3.2.9+)

The default test fixture for determining Ramp data has a 50 ohm resistor,
tied to power for falling data and tied to ground for rising data. The
initial and final values of the waveforms are used to define 20% and 80%
voltage points, where Ramp measurements are made. These test fixtures may
be similar to test fixtures used to produce Rising_waveform and
Falling_waveform data, in which case the data can be checked for
consistency. For example, a Rising Waveform with R_fixture = 50 and
V_fixture = 0.0 should have a 20% to 80% dt that is similar to the Ramp
dt_r value.

6. Each dV value matches within a factor of two 60% (80% - 20%)
   the difference between the initial and final voltages of the
   corresponding Rising_waveform or Falling_waveform with test fixture most
   similar to the Ramp test fixture.
   (level 0)

7. Each dt value matches within a factor of two the difference between
   the times of crossing the 20% voltage point and the 80% voltage
   point on the corresponding Rising_waveform or Falling_waveform with test
   fixture most similar to the Ramp test fixture.
   (level 0)

8. Each dt value matches within a factor of two the
   corresponding rise or fall time specified in the datasheet for a part pin
   using that buffer model.
   (level 1)

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