Subject: RE: [IBIS-Users] On-die DIFFERENTIAL terminated buffer modeling
From: Henrik G. Madsen (hgm@vitesse.com)
Date: Thu May 22 2003 - 23:37:41 PDT
Sk,
One solution could be to do the plain IBIS model for the LVDS input without termination, and then adding the termination as a discrete resistor in the simulation circuit.
The external termination resistor should of cause have the same properties as the 'deleted' internal.
Regards
Henrik G Madsen
-----Original Message-----
From: sk [mailto:wsk78@yahoo.com]
Sent: 23. maj 2003 03:16
To: Henrik G. Madsen; ibis-users@eda.org
Subject: RE: [IBIS-Users] On-die DIFFERENTIAL terminated buffer modeling
Henrik,
Thanks for the reply. I just found out that the tool
that I'm using does not support the series keywords.
So does anyone has a workaround for this?
Much Appreciated,
sk
--- "Henrik G. Madsen" <hgm@vitesse.com> wrote:
> Hi
>
> If you have the SPICE model for the LVDS cell, you
> can remove the build-in termination and model the
> LVDS input as normal.
> Then afterwards, you can model the termination alone
> and add it to the IBIS file using the 'Series' model
> type.
> Remember to add the termination pin info through the
> [Series Pin Mapping] keyword
>
> I have tried to illustrate the final IBIS model
> below.
>
> You have to be aware that certain IBIS tool still do
> not support the below approach fully.
>
> Regards
> /Henrik G Madsen
>
> Example
> .......
> |
> [Pin] signal_name model_name
> R_pin L_pin C_pin
> |
> pin1 LVDS_p LVDS_model
> pin2 LVDS_n LVDS_model
> |
> [Diff pin] inv_pin vdiff tdelay_typ tdelay_min
> tdelay_max
> |
> pin1 pin2 NA NA NA NA
> |
> [Series Pin Mapping] pin_2 model_name
> function_table_group
> |
> pin1 pin2 term_model
> |
>
|************************************************************************
> [Model] term_model
> Model_type Series
> C_comp 0pF 0pF
> 0pF
> |
> [Temperature Range] 55.000 120.00
> 0.0000
> [Voltage Range] 2.500V 2.300V
> 2.700V
> |
> |variable R(typ) R(min) R(max)
> [R Series] 100 120 80
> |
> |
> [Model] LVDS_model
> Model_type I/O
> Polarity Non-Inverting
> Enable Active-Low
> ........
>
> -----Original Message-----
> From: sk [mailto:wsk78@yahoo.com]
> Sent: 22. maj 2003 09:40
> To: ibis-users@eda.org
> Subject: [IBIS-Users] On-die DIFFERENTIAL terminated
> buffer modeling
>
>
> Hi all,
>
> Does anyone has experience modeling a LVDS input
> buffer with on-die differential termination?
>
> Can someone shed me some light here?
>
> Best Regards
>
>
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