RE: [IBIS-Users] V-t curves offset

Ramiro,

It sounds like you might be comparing the HSPICE output to the Ramp output. Check that you have specified for HSPICE to use the rising/falling waveforms, otherwise it defaults to using only the ramp data. Check the manual, but I think the keywords are: ramp_fwf = 1 and ramp_rwf = 1 to use 1 rising and 1 falling waveform. The default values are 0, so it uses none of the waveforms.

-----Original Message-----
From: owner-ibis-users@eda.org [mailto:owner-ibis-users@eda.org]On
Behalf Of RODRIGUEZ_LECONA_RAMIRO
Sent: Tuesday, October 12, 2004 5:36 PM
To: ibis-info@eda.org; ibis-users@eda.org
Subject: [IBIS-Users] V-t curves offset

Hi all,

     I'm working with IBIS models validation and I have a problem
correlating the IBIS model with transistor level buffer in HSPICE. I
simulate both buffers with the same conditions (same load, temperature,
voltage supply) and the rising/falling edges of the outputs are equal but
there is a delay between IBIS model output waveform and transistor level
buffer output waveform. I shift the V-t Tables in the IBIS model to
compensate the delay and the output waveforms are matched but this occurs
when the input signal has rising/falling times equal to the rising/falling
times used to extract the IBIS model, if I use a input signal with
rising/falling times lower than the rising/falling times used to extract the
V-t curves then the buffer implemented with the IBIS model has again a
delay.
   What happens?
   How can I understand this? How can I avoid this delay?
   Or this phenomenom is normal because the important thing is the edge
waveform (buffer switching behavior) and the delay obtained is not relevant?
   Or the V-t curves obtained with specyfic rise/fall times are only valid
to simulate buffers with input signals with the same rise/fall times ?

   Thanks.

   Regards.

|------------------------------------------------------------------
|For help or to subscribe/unsubscribe, email majordomo@eda.org
|with just the appropriate command message(s) in the body:
|
| help
| subscribe ibis <optional e-mail address, if different>
| subscribe ibis-users <optional e-mail address, if different>
| unsubscribe ibis <optional e-mail address, if different>
| unsubscribe ibis-users <optional e-mail address, if different>
|
|or email a written request to ibis-request@eda.org.
|
|IBIS reflector archives exist under:
|
| http://www.eda.org/pub/ibis/email_archive/ Recent
| http://www.eda.org/pub/ibis/users_archive/ Recent
| http://www.eda.org/pub/ibis/email/ E-mail since 1993

|------------------------------------------------------------------
|For help or to subscribe/unsubscribe, email majordomo@eda.org
|with just the appropriate command message(s) in the body:
|
| help
| subscribe ibis <optional e-mail address, if different>
| subscribe ibis-users <optional e-mail address, if different>
| unsubscribe ibis <optional e-mail address, if different>
| unsubscribe ibis-users <optional e-mail address, if different>
|
|or email a written request to ibis-request@eda.org.
|
|IBIS reflector archives exist under:
|
| http://www.eda.org/pub/ibis/email_archive/ Recent
| http://www.eda.org/pub/ibis/users_archive/ Recent
| http://www.eda.org/pub/ibis/email/ E-mail since 1993
Received on Tue Oct 12 17:55:34 2004