RE: [IBIS-Users] IBIS load

Hi Lynne,

Thanks for the reply. As mentioned in my earlier mail, if I use the 1.5K
resistor to simulate, it will use up to 100ns to stabilize. This will
affect my resolution especially for fall time, since each step is only
1ns and my fall time is less than 10ns. Is it ok to just have 50 Ohm V-T
table (which has rise time <10ns), since this will provide a good
resolution for both the rise and fall time?

Best regards,
Mei Yee
SID, Avago Technologies (Malaysia)
Tel no.:604-6108515

-----Original Message-----
From: Lynne D. Green [mailto:lgreen22@mindspring.com] 
Sent: Tuesday, December 05, 2006 11:56 AM
To: NG,MEI-YEE; ibis-users@eda.org
Subject: RE: [IBIS-Users] IBIS load

Hello, Mei-Yee,
 
The 1.5K resistor is needed for bias control for an
open-source/open-sink
buffer.  In addition to that resistor, one needs a V-t load (the 50 ohms
you
refer to).  The 50 ohm load is described in the IBIS Cookbook,
http://www.vhdl.org/pub/ibis/cookbook/cookbook-v4.pdf.
 
This means your simulation will have both resistors: the 1.5K and the 50
ohms.
 
Once you have completed your model, please feel welcome to submit your
model
to the IBIS Model Review Committee,
http://www.eigroup.org/ibis/support.htm.
 
Best regards,
Lynne
 
 
 
"IBIS training when you need it, where you need it."
 
Dr. Lynne Green
Green Streak Programs
http://www.greenstreakprograms.com
425-788-0412
lgreen22@mindspring.com
 
 



________________________________

	From: owner-ibis-users@eda.org [mailto:owner-ibis-users@eda.org]
On
Behalf Of NG,MEI-YEE
	Sent: Monday, December 04, 2006 5:28 PM
	To: ibis-users@eda.org; ibis-users@eda.org
	Subject: [IBIS-Users] IBIS load
	
	

	Hi experts,

	 

	According to the cookbook, when extracting V-T data, it is
recommended to use a load circuit of 1R + 1F into manufacturer's
suggested
pullup resistor termination and voltage. However, when I use the
suggested
pullup resistor (1.5K), the rising waveform takes up to 100ns to
stabilize,
but the falling waveform requires less than 10ns. This creates
inaccuracy
due to the resolution of the points (when I use 100ns simulation time).
In
the IBIS model, I also included a waveform for 50Ohm pullup resistor (as
recommended by cookbook). The rising waveform for this is also within
10ns.
I wonder if I can generate IBIS model with ONLY 50 Ohm pullup because
the
resolution is more appropriate in this case? I have verified this model
and
the simulation shows acceptable waveforms.

	 

	Kindly advice whether it is a MUST to have a 1.5K pullup
resistor
V-T table.

	 

	Thank you.

	 

	Best regards,

	 

	Mei Yee Ng

	IC Design Engineer 

	Illumination and Color Management

	Solid-state Illumination Division

	Avago Technologies Malaysia

	Tel no: +604-6108515

	 




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