|
[si-list]
||
[Date Prev]
[11-2002 Date Index]
[Date Next]
||
[Thread Prev]
[11-2002 Thread Index]
[Thread Next]
[SI-LIST] Re: Basic IBIS I/V curve question
- From: "Muranyi, Arpad" <arpad.muranyi@xxxxxxxxx>
- To: <si-list@xxxxxxxxxxxxx>
- Date: Thu, 7 Nov 2002 08:03:46 -0800
What hasn't been mentioned yet is that the IV curves represent the =
buffer
strength at the specified voltage, temperature and process corner.
So, for example, the minimum IV curve of a 5 V device would usually be
extracted at 4.75 V, 100 C and using the slow process file. This gives
the weakest IV curve for that device. If you extracted an other IV =
curve
from this device changing only the supply voltage to, say, 5 V, you =
should
get stronger IV curves for both pullup and pulldown.
It is true that in the simulation you can power the 4.75 V model with 5 =
V
(or even 5.25 if you want), but that will only shift the pullup IV =
curve's
origin higher without changing it's shape. This will not be the same as
extracting the IV curves at 5 V! What this means is that the IV curves =
remain
the same, except the pullup will pull to a higher voltage. Compare this =
with
the real device. If you raise the supply voltage, the IV curves will =
get
larger due to the higher gate voltages, as well as the pullup IV curve =
being
shifted to a higher voltage.
I hope this will help clarifying your question.
Arpad Muranyi
Intel Corporation
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
-----Original Message-----
From: Gustavo Blando [mailto:gblando@xxxxxxxxxxxx]
Sent: Thursday, November 07, 2002 7:41 AM
To: 'marko.pulli@xxxxxxxxx'; Andrew.Ingraham@xxxxxx
Cc: si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Re: Basic IBIS I/V curve question
I am confused here. I though that even though the curves are VCC =
relative on
IBIS
it does matter the voltage at which the VI curves where extracted.
If you go and change the voltage range on the model, Yes the IV curve =
will
now be referenced to a different voltage, but that does not mean =
necesarely
that the IV
curve is correct now.=20
Changing the voltage as Andrew said, "depending on the driver" will =
change
the characteristics of the drive strength.
Thanks.
Gus.
-----Original Message-----
From: marko.pulli@xxxxxxxxx [mailto:marko.pulli@xxxxxxxxx]
Sent: Thursday, November 07, 2002 10:01 AM
To: Andrew.Ingraham@xxxxxx
Cc: si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Re: Basic IBIS I/V curve question
Hi,
I was misled by one thing in my simulator.
You are absolutely right that the curves are independent of min/max =3D
voltage.
It looks like the simulator always uses the min and max from what is =3D
defined in the IBIS model [Voltage range] line.
I was trying to set the minimum and maximum voltage in the simulator =3D
environment but it doesn't seem to work.
Now I have changed the [Voltage range] section in the model itself to =
=3D
correspond the actual min and max in my design..
Thanks for guiding me back into the right path!
Br,
Marko
> -----Original Message-----
> From: ext Ingraham, Andrew [mailto:Andrew.Ingraham@xxxxxx]
> Sent: 07. November 2002 14:52
> To: si-list@xxxxxxxxxxxxx; Pulli Marko (NET/Espoo)
> Subject: [SI-LIST] Re: Basic IBIS I/V curve question
>=3D20
>=3D20
> Ideally, the three I-V curves would be independent of the operating
> supply voltage. The curves are Vcc-relative, so each of the three
> curves could be used with any supply voltage within the=3D20
> normal operating
> range.
>=3D20
> The minimum I-V curve is supposed to represent slow/weak=3D20
> silicon (due to
> IC processing variations) at whatever temperature results in slow/weak
> operation (high temp. for MOS, low temp. for bipolar). Since=3D20
> the supply
> voltage typically does influence device drive strength and speed, the
> minimum I-V curve is usually extracted when the supply voltage is also
> at minimum.
>=3D20
> I don't know how you can tell that the minimum I-V curve=3D20
> corresponds to
> any operating voltage. It shouldn't have any clues about the=3D20
> operating
> voltage.
>=3D20
> If you question whether the minimum I-V curve is valid, you should
> discuss this with the IC vendor or whoever made the IBIS=3D20
> model. Without
> that discussion, one should assume that the minimum I-V curve truly
> represents a worst-case device.
>=3D20
> Regards,
> Andy
>=3D20
>=3D20
>=3D20
> ------------------------------------------------------------------
> To unsubscribe from si-list:
> si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field
>=3D20
> or to administer your membership from a web page, go to:
> http://www.freelists.org/webpage/si-list
>=3D20
> For help:
> si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field
>=3D20
> List archives are viewable at: =3D20
> http://www.freelists.org/archives/si-list
> or at our remote archives:
> http://groups.yahoo.com/group/si-list/messages=3D20
> Old (prior to June 6, 2001) list archives are viewable at:
> http://www.qsl.net/wb6tpu
> =3D20
>=3D20
>=3D20
------------------------------------------------------------------
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: =20
http://www.freelists.org/archives/si-list
or at our remote archives:
http://groups.yahoo.com/group/si-list/messages=20
Old (prior to June 6, 2001) list archives are viewable at:
http://www.qsl.net/wb6tpu
=20
------------------------------------------------------------------
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: =20
http://www.freelists.org/archives/si-list
or at our remote archives:
http://groups.yahoo.com/group/si-list/messages=20
Old (prior to June 6, 2001) list archives are viewable at:
http://www.qsl.net/wb6tpu
=20
------------------------------------------------------------------
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
|
|
