RE: [IBIS-Users] Query reg. USB1.1 IBIS model generation

Vivek,
 
R_fixture has nothing to do with the 1.5k or 15k resistors.
Select a value for R_fixture that matches the transmission
line impedance.  In the USB case it would be 45 Ohms (single
ended) if my memory serves me right.
 
I would also suggest that you look at the IBIS Cookbook for
help.  There are a lot of good ideas in there.
 
http://www.vhdl.org/pub/ibis/cookbook/cookbook-v4.pdf
 
Arpad
=============================================================


________________________________

From: owner-ibis-users@server.eda.org
[mailto:owner-ibis-users@server.eda.org] On Behalf Of Vivek kumar Singh
Sent: Sunday, January 20, 2008 10:34 PM
To: ibis-users@server.eda.org; ibis@server.eda.org
Cc: Vijaya kumar Vinukonda
Subject: [IBIS-Users] Query reg. USB1.1 IBIS model generation



Hi All,

    I'm having problem with ibis model generation for USB1.1 . 

I have following 3 queries :

 

1)       since USB operates in Upstream and Downstream applications with
pullup and pulldown resistors 1.5k and 15k Ohm respectively. Will it
have any effect on choosing R_fixture value for IBIS VT data generation
????

 

2)       What actually we take the value of R_fixture for USB1.1 ?

 

3)       Can someone elaborate on setup for Ibis model generation for
USB1.1.

 

 

Regards,

Vivek

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