RE: [IBIS-Users] Need help with IBIS/ECL question

Subject: RE: [IBIS-Users] Need help with IBIS/ECL question
From: Lynne Green (lgreen@cadence.com)
Date: Mon Mar 17 2003 - 13:15:56 PST

Next message: Peters, Stephen: "[IBIS-Users] Agenda, IBIS Open Forum Meeting 2/28"
Previous message: Jeremy Plunkett: "RE: [IBIS-Users] Need help with IBIS/ECL question"
Maybe in reply to: John Gunser: "[IBIS-Users] Need help with IBIS/ECL question"
Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]

Other tools, including SPECCTRAQuest, allow you to set up
the correct ECL rail voltages.

The problem is that many IBIS models, particularly inputs, tend to
use the [Voltage Range] keyword, which makes the implied reference
voltages for the PullDown and GroundClamp (zero volts) incorrect.

- Lynne

-----Original Message-----
From: Jeremy Plunkett [mailto:jeremy@serverworks.com]
Sent: Friday, March 14, 2003 6:38 PM
To: Beal, Weston; gunser@lucent.com; ibis-users@eda.org
Subject: RE: [IBIS-Users] Need help with IBIS/ECL question

John,
I suggest you use a simulator that allows you to set up the supply rails
to the IBIS model yourself, rather than generating the supply
connections internally. This way there is no need to modify your IBIS
model.

The only such tool I am aware of is Hspice, but other simulators may
allow this also with some special option. In Hspice, you'll need to set
power=off, connect the pullup and power clamp nodes to your GND rail and
the pulldown and groundclamp nodes to the -5v rail, and connect a 5v
voltage source (and a power delivery model if you have it) with the +
node on GND.

The signals that control the IBIS model on the "core" side don't have
any relationship to the IO rails so they will still need to switch from
0-1v.

I haven't tried this myself but as far as I know it should work.

Jeremy

-----Original Message-----
From: owner-ibis-users@server.eda.org
[mailto:owner-ibis-users@server.eda.org]On Behalf Of Beal, Weston
Sent: Friday, March 14, 2003 9:07 AM
To: ibis-users@server.eda.org
Subject: RE: [IBIS-Users] Need help with IBIS/ECL question

John,

I don't recall anything in the IBIS specification that prohibits this
method, but the more important issue is whether or not your simulator
will interpret it as you desire. I kind of doubt that this will work in
any of the simulators that I'm familiar with.

If I were in your position, I would just try one simple model and try a
simulation in my favorite simulator. You'll need to remove any rising
and falling waveforms for the first test, as they surely will cause
confusion. If you find that the first test works and you want to add the
waveforms back in, then you'll have to find a method to adjust the
voltage values to line up with your new model.

Good Luck,
Weston

-----Original Message-----
From: John Gunser [mailto:gunser@lucent.com]
Sent: Friday, March 14, 2003 4:54 AM
To: ibis-users@server.eda.org
Subject: [IBIS-Users] Need help with IBIS/ECL question

Hi All,

I have a few questions I was hoping someone here could help me out with.

Background: I am attempting to perform signal integrity on a 10-15 year
old circuit pack that uses the 100K series of ECL devices. This pack is
being redesigned to replace some DA components and we need to verify the
quality of the other signals. On this circuit pack, these ECL devices
interface to standard 74F, ABT and HC devices that are connected and
operating "under water" (with VCC tied to ground and GRD connected to -5
volts) I have obtained ibis models for the 74F, ABT and HC parts but now
need to modify them to correctly reflect how they are being used in the
circuit.

Questions: Can I simply change the pull up, pull down, ground clamp and
power clamp reference values to reflect the -5V to 0 operation rather
than 0 to
+5V?
For Vinl, am I correct in assuming it should change to .8V more than -5
or -4.2 volts? Similarly Vinh would be -5 + 2 = -3?? In the output model
where Vmeas and Vref are specified (currently 1.5V and 0v), If I change
the Vref to -5V, is the Vmeas specified to be relative to the Vref (1.5V
more than Vref) or is Vmeas absolute and need to be specified as -3.5V?
Any help in sorting this out will be greatly appreciated! Thanks in
advance!

Best Regards
John Gunser
gunser@lucent.com
|------------------------------------------------------------------
|For help or to subscribe/unsubscribe, email majordomo@eda.org with just

|------------------------------------------------------------------
|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

Next message: Peters, Stephen: "[IBIS-Users] Agenda, IBIS Open Forum Meeting 2/28"
Previous message: Jeremy Plunkett: "RE: [IBIS-Users] Need help with IBIS/ECL question"
Maybe in reply to: John Gunser: "[IBIS-Users] Need help with IBIS/ECL question"
Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]

This archive was generated by hypermail 2b28 : Mon Mar 17 2003 - 13:29:44 PST