RE: [IBIS-Users] Bus Switch IBIS Models

From: Muranyi, Arpad <Arpad_Muranyi@mentor.com>
Date: Mon Oct 25 2010 - 17:03:29 PDT

Tim,

 

It all depends on the device, but in the off state I

would not expect it to have any significant series

current that you would need to model with [Series

Current]. Series bus switches are usually in a fairly

high impedance state when they are turned off...

 

Arpad

=======================================================

 

 

From: Timothy Coyle [mailto:tim.coyle@siconsultant.com]
Sent: Friday, October 22, 2010 12:50 PM
To: 'Mike LaBonte'; Muranyi, Arpad; 'IBIS'
Subject: RE: [IBIS-Users] Bus Switch IBIS Models

 

How about when the switch is in the Off state. Is there a situation
where you need to simulate that with actual data such as [Series
Current] or is [R Series] sufficient? Does the EDA tool just need a way
to disable the switch in a batch mode type simulation?

 

Thanks

 

Tim

 

 

From: Mike LaBonte [mailto:milabont@cisco.com]
Sent: Friday, October 22, 2010 11:04 AM
To: Arpad Muranyi; Timothy Coyle; IBIS
Subject: Re: [IBIS-Users] Bus Switch IBIS Models

 

More exactly, IBIS does not have time profile data to model the
transition of a series switch between on and off states. It is certainly
possible to convert the IBIS series switch model data to a circuit model
using table elements, in which a control signal makes the switch
transition dynamically from on to off and vice-versa. The switching time
profile would have to be set by the control signal. I believe the
Cadence implementation works this way, but I have heard of only one
instance of someone using the capability (experimentally).

I agree with Tim that automation of [Series Switch Groups] and on/off
control at the EDA tool end is lacking. I think Tim is asking the right
question, "does anyone really need it?"

Mike

On 10/22/10 10:25 AM, "Arpad Muranyi" <Arpad_Muranyi@mentor.com> wrote:

Tim,
 
IBIS doesn't support modeling the transitions between the On/Off state.
The assumption is that this is not changing during simulations. There
is no information in the models that describes how these devices would
transition from one state to the other. We would need something like
the V-t tables in order to do that, but they don't exist for this
purpose.
 
Arpad
=======================================================================
 

From: owner-ibis-users@eda.org [mailto:owner-ibis-users@eda.org] On
Behalf Of Timothy Coyle
Sent: Thursday, October 21, 2010 11:35 AM
To: ibis-users@eda.org
Subject: [IBIS-Users] Bus Switch IBIS Models

Hi,
When you have MOSFET switch and model it using [Series Mosfet] keyword
in IBIS there are two ways to pin map it. The first way is to use
[Model] Series and just use [Series Pin Mapping] and this assumes that
the switch is always in On state. The other way is to use [Model]
Series_switch with [Series Pin Mapping] and [Series Switch Groups] and
this way there can be configured On and Off states. However I have found
that most simulation/cad tools do not fully support [Series Switch
Groups] without manual modification by end user. Modeling the switch as
a Series device just Series Pin Mapping seems to be the default
supported state.
 
Has anyone else seen this issues of Series Switch Groups not being
supported? Even when I do some modifications for a tool to support it
many do not seem to use the Off state data. I would also be interested
to hear of the simulation usage case where someone needs the ability to
switch between On and Off states.
 
Thanks,
 
Timothy Coyle
President
Signal Consulting Group LLC
405 Western Ave #430
South Portland, ME 04106
Tel: 617.297.2566
Email: tim.coyle@siconsultant.com <mailto:tim.coyle@siconsultant.com>
Web: http://www.siconsultant.com <http://www.siconsultant.com/>
SharkSim <http://www.sharksim.com/> - Signal Integrity IBIS Modeling
Software

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Received on Mon Oct 25 17:04:04 2010

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