[SI-LIST] Re: HSPICE Vs. IBIS models
- From: "Gil Gafni" <gil.gafni@xxxxxxxx>
- To: <a.ingraham@xxxxxxxx>, "'Si-List'" <si-list@xxxxxxxxxxxxx>
- Date: Thu, 22 Jan 2004 17:00:37 -0800
Hi Andy,
Yes from what I see the waveforms are pretty much alike, only shifted by
30 to 350 pico second, depends on the nature of the load. For a resistor
it is less where as for a capacitor it is more.
Do you know how HSPICE uses/parses the C_ref, R_ref and V_ref?
If I understand it right, these parameters are the load that was
attached to the HSPICE model while creating the IBIS model.
If I am right, then the IBIS has some delay embedded (due to the delay
influence of the load)
Gil
-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx]
On Behalf Of Ingraham, Andrew
Sent: Thursday, January 22, 2004 10:50 AM
To: Si-List
Subject: [SI-LIST] Re: HSPICE Vs. IBIS models
> Generally - the signal are alike, the only issue is that the when I
> simulate with the IBIS model the timing is lagging by about 200ps in
> the Slow corner and 50ps in the Fast corner.
Do you mean that the waveforms compare well, but that they are shifted
in time?
IBIS models model just the output portion of the output buffer, just the
part of the circuit that interacts with the external circuit
connections.
SPICE models can represent the output transistors, or the whole output
buffer, or the whole IC if you want. Each case would give the SPICE
simulation a different delay from input-to-output of the SPICE model.
You could even have a SPICE model of an output buffer that has a 500ns
delay-line in it; but when you convert it to IBIS (without
rising/falling waveforms), that delay information is gone. IBIS just
gives you a simulation of what the output waveform looks like, with no
absolute timing reference. (HSPICE's implementation of IBIS does give
you a "buffer" which seems to have a stimulus input "pin" and a delay,
but it's artificial.)
Even if the IBIS model had rising/falling waveform tables, simulators
don't need to use them.
Regards,
Andy
------------------------------------------------------------------
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:
//www.freelists.org/webpage/si-list
For help:
si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field
List technical documents are available at:
http://www.si-list.org
List archives are viewable at:
//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:
//www.freelists.org/webpage/si-list
For help:
si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field
List technical documents are available at:
http://www.si-list.org
List archives are viewable at:
//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
Other related posts:
