RE: [IBIS-Users] RE: A newbie question

Hi Lior,

It sounds like you may be asking how do you use a differential IBIS buffer
in Spectre if you have it setup as a single-ended buffer with [Diff Pin]
keyword in IBIS? If so then it will depend on how Spectre uses IBIS models.
I think the way Spectre does it is that it will make you create two
instances of your single-ended buffer and then you can use the differential
outputs. So you could create a new block that calls each single-ended model
and have the corresponding differential output. You will probably have to
either apply inverting input signal to one of the single-ended buffers to
get inverting output or create a copy of single-ended buffer that has
Polarity keyword set to Inverting.

I think in most SPICE tools like Spectre and HSPICE when using [Diff Pin]
keyword by default you have to treat them as single-ended buffer and hook
them up as pseudo-differential buffer in your netlist. (Of course you should
consult the user guide as some tools have more features than others) As you
are probably aware in most Signal Integrity tools where you have a schematic
topology entry tool you can just drop down a differential driver component
and then the EDA tool will actually use the [Diff Pin] keyword and give you
settings to configure it properly.

So if you need to setup in Spectre to use this IBIS model ignore the [Diff
Pin] keyword and manually create an instance of your differential buffer by
hooking up your single-ended buffers as a pseudo-differential buffer.

Hope this helps

Best,

Timothy Coyle

President

Signal Consulting Group LLC

405 Western Ave #430

South Portland, ME 04106

Tel: 617.297.2566

Email: <mailto:tim.coyle@siconsultant.com> tim.coyle@siconsultant.com

Web: <http://www.siconsultant.com/> http://www.siconsultant.com

 <http://www.sharksim.com/> SharkSim - Signal Integrity IBIS Modeling
Software

From: owner-ibis-users@eda.org [mailto:owner-ibis-users@eda.org] On Behalf
Of Lior Dagan
Sent: Tuesday, July 26, 2011 8:44 AM
To: naftali refaeli; ibis-users@eda.org
Subject: [IBIS-Users] RE: A newbie question

1st of all, thanks.

No, it's not s2ibis, I can't use it here.

It's a script which takes measurements, and then inserts them to the model.

I can model a single ended buffer.

But say I have out_pin1, and out_pin2, same single ended open_sink, which
are connected via [Diff Pin] model.

How do I create 1 instance, which has two pins in_1 and in_2, which drives
them?

I am also trying to see if they'd go for using two instances which call for
models, w/o referring to the pins' names.

I need it for my customer's customers.

-Lior

From: naftali refaeli [mailto:Naftali.Refaeli@ecitele.com]
Sent: Tuesday, July 26, 2011 3:34 PM
To: Lior Dagan
Subject: RE: A newbie question

What tool do you use for IBIS? Is it s2ibis?

Can you model a single (not diff) buffer?

Naftali Refaeli

CAE Engineer

ITO

HP Enterprise Services

Telephone +972 3.9266973

Mobile +972 52.3542043

Email Naftali.Refaeli@ecitele.com

From: owner-ibis-users@eda.org [mailto:owner-ibis-users@eda.org] On Behalf
Of Lior Dagan
Sent: Tuesday, July 26, 2011 3:24 PM
To: ibis-users@eda.org
Subject: [IBIS-Users] A newbie question

Hello all.

I am writing a model for my customers.

Their requirements are:

Use version 3.2.

2 Differential Open_sink pins.

Use the IBIS full component model (i.e, not a pin model but connect the
whole block).

Use Spectre.

The question is: How do I define for the instance it's input pins (that
stimulate the two open_sink pins)?

I have looked at both Cadence manuals and yours, and could not find an
answer..

Thanks,

Lior Dagan, CAD engineer @ TranSwitch

Cell: +972-52-3401068

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