FreeLists / si-list / [SI-LIST] Re: (no subject)

[Umesh Painaik <upainaik@xxxxxxxxxxxx>]

Hi Paul
The ibis checker checks the VI curves v/s the VT curves in the file.
It will draw a load lines .e.g. if the test fixtures are 50 to VCC and 50 to
GND, there will be two load lines. The 50 to VCC will pass through the
pulldown or low curve and the 50 to GND will pass through the pullup or high
curve. Hence it predicts what the voltage swings will be like if these VI
curves were loaded with the above test fixtures.
It will not predict the shape or time.
When it compares these values with the actual values in the waveforms and if
differences exist then, the checker will give warning message.
Looking at your message, I wouldn't worry about the 0.01V difference, the
1.45-1.20= 0.25V would be of some concern.
here are some of the reasons why the DC and transient waveforms differ.
1) If spice doesnot converge properly in either DC or transient simulations
the mismatch could occur.
2) This is a multistage driver, and it is not modeled properly.
3) There could be package effects in the transient curves
this almost always warrants closer look at the ibis model and also the
source e.g. spice

Hope this helps
Umesh Painaik
Innoveda Consulting

-----Original Message-----
From: Paul Fernando [mailto:rukf@xxxxxxxxxxx]
Sent: Friday, June 07, 2002 10:21 AM
To: si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] (no subject)


Does anyone know what this means & how to resolve it? Its produced when
I check an ibs file on Innoveda's Visual IBIS editor.
Thanks.
Paul

ERROR - Model driver: The [Rising Waveform]
      with [R_fixture]=500 Ohms and [V_fixture]=0V
      has TYP column DC endpoints of  0.01V and  1.20v, but
      an equivalent load applied to the model's I-V tables yields
      different voltages ( 0.00V and  1.45V),
      a difference of 54208654.45% and 17.00%, respectively.

------------------------------------------------------------------
To unsubscribe from si-list:
si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field

or to administer your membership from a web page, go to:
http://www.freelists.org/webpage/si-list

For help:
si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field

List archives are viewable at:
                http://www.freelists.org/archives/si-list
or at our remote archives:
                http://groups.yahoo.com/group/si-list/messages
Old (prior to June 6, 2001) list archives are viewable at:
                http://www.qsl.net/wb6tpu

------------------------------------------------------------------
To unsubscribe from si-list:
si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field

or to administer your membership from a web page, go to:
http://www.freelists.org/webpage/si-list

For help:
si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field

List archives are viewable at:     
                http://www.freelists.org/archives/si-list
or at our remote archives:
                http://groups.yahoo.com/group/si-list/messages 
Old (prior to June 6, 2001) list archives are viewable at:
                http://www.qsl.net/wb6tpu