Re: [IBIS-Users] LVDS RECEIVER TERMINATION Question

Subject: Re: [IBIS-Users] LVDS RECEIVER TERMINATION Question
From: Adam.Tambone@fairchildsemi.com
Date: Tue Jul 23 2002 - 06:23:58 PDT

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Hello Peter,

I have an additional question regarding what you have described below. If
the LVDS receiver has an internal 100 Ohm termination across two LVDS
inputs, then when the I-V measurements are taken for one input, how is the
partner input being treated? Is it left floating?

Thaks,
Adam

|---------+--------------------------->
| | Peter LaFlamme |
| | <plaflamm@amcc.c|
| | om> |
| | Sent by: |
| | owner-ibis-users|
| | @eda.org |
| | |
| | |
| | 07/23/02 09:01 |
| | AM |
| | |
|---------+--------------------------->
>-------------------------------------------------------------------------------------------------------------------------------|
  | |
  | To: ibis-users@eda.org |
  | cc: |
  | Subject: [IBIS-Users] LVDS RECEIVER TERMINATION Question |
>-------------------------------------------------------------------------------------------------------------------------------|

Hi All,
I am tasked with creating an IBIS model for an LVDS receiver cell that has
an internal 100 ohm termination between the P and N nodes. I had asked Bob
Ross about this a while ago and as usual he was very helpful. From his
response I used the following
implementation:

|****************************************************************
| Component: LVDSRCV
|****************************************************************
|
[Component] LVDSRCV
[Manufacturer] AMCC
|
|
|
[Package]
| variable typ min max
R_pkg 1E-3 NA NA
L_pkg 1E-9 NA NA
C_pkg 1E-12 NA NA
|
[Pin] signal_name model_name R_pin L_pin C_pin
1 PAD lvdsrcv NA NA NA
2 PADN lvdsrcv NA NA NA
|
[Series Pin Mapping] pin_2 model_name function_table_group
1 2 rterm_100

|
[Diff_pin] inv_pin vdiff tdelay_typ tdelay_min
tdelay_max
|
1 2 0.2 0 0 0

[Model] rterm_100
C_comp 0.1pF 0.1pF 0.1pF

Model_type Series
|variable R(typ) R(min) R(max)
[R Series] 100 80 120

[Temperature Range] 25.00 125.00 0.00
[Voltage Range] 1.800 1.650 1.950

****************************************************************************************

I was able to get the model past the IBIS checker but my simulations did
not show the 100 ohm terminator. I was using a tool which I believe does
not support this implementation (no need to mention names). I have seen
other implementations where I believe
a "Dynamic clamp" is used to model the termination behavior, but I am
unsure. Can anyone guide me to some reference material or weigh in with
your experience or help.

Thanks alot,
Peter

--
Peter LaFlamme
Applied Micro Circuits Corp.
System Applications Engineer
200 Minuteman Rd, 3rd Floor
Andover, MA 01810
978-247-8470 phone
978-623-0055 Fax
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