[ibis-macro] Re: redriver in spice simulation

  • From: <radek_biernacki@xxxxxxxxxxx>
  • To: <fangyi_rao@xxxxxxxxxxx>, <twesterh@xxxxxxxxxx>, <ambrishv@xxxxxxxxxxx>
  • Date: Wed, 13 Mar 2013 10:48:41 -0600

Hi All,

I think a very simple solution is to limit the scope of the [Repeater Pin] to 
AMI applications. In legacy IBIS simulations that keyword can simply be 
ignored, exactly the same way the keyword [Algorithmic Model] is ignored today.

Also, the Maxim-Agilent BIRD on redrivers can go as is. When the repeater BIRD 
is ratified, it can simply then apply to redrivers (and perhaps repeaters).

Radek

From: ibis-macro-bounce@xxxxxxxxxxxxx [mailto:ibis-macro-bounce@xxxxxxxxxxxxx] 
On Behalf Of fangyi_rao@xxxxxxxxxxx
Sent: Wednesday, March 13, 2013 9:11 AM
To: twesterh@xxxxxxxxxx; ambrishv@xxxxxxxxxxx
Cc: ibis-macro@xxxxxxxxxxxxx
Subject: [ibis-macro] Re: redriver in spice simulation

Hi, Todd;

We got into this discussion because if we introduce a new keyword for 
redriver/repeater such as the one in Walter’s repeater BIRD, we will have to 
define the redriver behavior in non-AMI simulations. That’s why I didn’t 
introduce new keyword in the Maxim-Agilent redriver BIRD and limited it to the 
AMI context.

Regards,
Fangyi

From: Todd Westerhoff [mailto:twesterh@xxxxxxxxxx]
Sent: Wednesday, March 13, 2013 8:48 AM
To: 'Ambrish Varma'
Cc: RAO,FANGYI (A-USA,ex1); 
ibis-macro@xxxxxxxxxxxxx<mailto:ibis-macro@xxxxxxxxxxxxx>
Subject: RE: [ibis-macro] Re: redriver in spice simulation

Ambrish,

If you’re not including the algorithmic part, then the equalization isn’t 
getting modeled.  Why bother?

Todd.


Todd Westerhoff
VP, Software Products
Signal Integrity Software Inc. • www.sisoft.com<http://www.sisoft.com>
6 Clock Tower Place • Suite 250 • Maynard, MA 01754
(978) 461-0449 x24  •  twesterh@xxxxxxxxxx<mailto:twesterh@xxxxxxxxxx>

“I want to live like that”
                                             -Sidewalk Prophets

From: Ambrish Varma [mailto:ambrishv@xxxxxxxxxxx]
Sent: Wednesday, March 13, 2013 11:46 AM
To: Todd Westerhoff
Cc: fangyi rao; ibis-macro@xxxxxxxxxxxxx<mailto:ibis-macro@xxxxxxxxxxxxx>
Subject: RE: [ibis-macro] Re: redriver in spice simulation

Todd,
We were discussing how a normal time domain (non-AMI) simulation will work with 
a redriver in the middle of a channel. I suggested that shorting the redriver 
Rx pins with the related Tx should work as the simulator will take care of the 
analog waveforms going out from the Rx and in the Tx – but that will not work 
as we describe below.

Thanks,
Ambrish.

From: Todd Westerhoff [mailto:twesterh@xxxxxxxxxx]
Sent: Tuesday, March 12, 2013 9:24 PM
To: Ambrish Varma
Cc: fangyi rao; ibis-macro@xxxxxxxxxxxxx<mailto:ibis-macro@xxxxxxxxxxxxx>
Subject: Re: [ibis-macro] Re: redriver in spice simulation

Ambrish,

I guess I missed part of this conversation.  What problem are you trying to 
solve?

Todd.

Todd Westerhoff
VP, Software Products
Signal Integrity Software Inc. • www.sisoft.com
6 Clock Tower Place • Suite 250 • Maynard, MA 01754
(978) 461-0449<978-461-0449> x24  •  twesterh@xxxxxxxxxx
“I want to live like that”
                                             -Sidewalk Prophets

________________________________
From: "Ambrish Varma" <ambrishv@xxxxxxxxxxx<mailto:ambrishv@xxxxxxxxxxx>>
To: "fangyi rao" <fangyi_rao@xxxxxxxxxxx<mailto:fangyi_rao@xxxxxxxxxxx>>, 
ibis-macro@xxxxxxxxxxxxx<mailto:ibis-macro@xxxxxxxxxxxxx>
Sent: Tuesday, March 12, 2013 7:34:02 PM
Subject: [ibis-macro] Re: redriver in spice simulation
Fangyi,
Actually, if we short the Rx and Tx of the redriver, regular spice simulations 
using IBIS models and analog repeaters will have issues with the Tx trying to 
pullup to power and pulldown to ground.

In that case, redriver simulation within the realm of an IBIS cct, solutions 
can be:


1)      No  spice (non AMI) simulation allowed for redrivers (easier)

2)      Series switch like implementation (harder)

Thanks,
Ambrish.

From: fangyi_rao@xxxxxxxxxxx<mailto:fangyi_rao@xxxxxxxxxxx> 
[mailto:fangyi_rao@xxxxxxxxxxx]
Sent: Tuesday, March 12, 2013 4:58 PM
To: Ambrish Varma; ibis-macro@xxxxxxxxxxxxx<mailto:ibis-macro@xxxxxxxxxxxxx>
Subject: redriver in spice simulation

Hi, Ambrish;

I am not sure if your suggestion of shorting redriver Rx ibis output pin to the 
redriver Tx ibis input pin in spice simulations will work because in spice 
simulations


1.       legacy Tx ibis model is driven by input signal threshold crossing 
events. That’s not how a redriver Tx half is driven by input signal.

2.       legacy Rx ibis model output is a digital signal of 1’s and 0’s 
(hopefully I am correct here). That’s not what redriver Rx half outputs.

Due to the uncertainties in redriver model behavior in non-AMI simulations, I 
prefer to keep my redriver BIRD separate from Walter’s repeater BIRD, at least 
for now.

Regards,
Fangyi


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