RE: [IBIS-Users] Differential Buffer Modelling

Paul,
 
I am not sure I understand what feedback you
are referring to.  Could you please explain?
Legacy IBIS models are not able to model feedback
anyway, so I am not sure what the context is for
this question.
 
Arpad
=================================================


________________________________

From: owner-ibis-users@eda.org [mailto:owner-ibis-users@eda.org] On Behalf Of Paul Fernando
Sent: Tuesday, October 04, 2005 12:05 PM
To: Muranyi, Arpad; ibis-users@eda.org
Subject: Re: [IBIS-Users] Differential Buffer Modelling


Arpad,

In differential buffers that contain common mode feedback, wouldn't it be more accurate to disconnect the feedback circuit before following this technique?

Regards,
Paul

Muranyi, Arpad wrote: 

	Kong-Yew,

	 

	1) Yes, you can apply this technique to receivers with ODT too.

	 

	2) I can't tell you which tool supports these keywords.  You

	should ask the vendors or try the tool and see what happens.

	 

	Arpad

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


________________________________

	From: owner-ibis@eda.org [mailto:owner-ibis@eda.org] On Behalf Of Kong Yew Chan
	Sent: Tuesday, October 04, 2005 3:27 AM
	To: ibis-users@eda.org; ibis@eda.org
	Subject: RE: [IBIS-Users] RE: [IBIS] Differential Buffer Modelling
	
	

	Thanks Arpad! I have further questions, hope you don't mind.

	 

	1)       Is this method of measuring differential current applicable to "receiver" with on-die termination?

	2)       How does simulators interpret the [Series Current] keyword? Do they automatically apply the series [Model] upon locating the [Series Pin Mapping] information when the pins are used? Which simulator currently supports this keyword? HSPICE? Hyperlynx? 

	 

	Thanks.

	Kong-Yew

	 

	
________________________________


	From: owner-ibis-users@eda.org [mailto:owner-ibis-users@eda.org] On Behalf Of Muranyi, Arpad
	Sent: Monday, October 03, 2005 11:49 PM
	To: ibis-users@eda.org; ibis@eda.org
	Subject: [IBIS-Users] RE: [IBIS] Differential Buffer Modelling

	 

	Kong-Yew,

	 

	1)  You are correct.  You would use Idiff and Vdiff for the table

	    in [Series Current].

	2)  You should use the same response (except with negative polarity)

	    for the cancellation that you will use in your final model.  If

	    it was an [R Series], use a negative resistance, if it was [Series

	    Current], use the same PWL table (with the signs reversed).

	 

	I hope this helps.

	 

	Arpad Muranyi

	Intel Corporation

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

	 

	
________________________________


	From: owner-ibis@eda.org [mailto:owner-ibis@eda.org] On Behalf Of Kong Yew Chan
	Sent: Monday, October 03, 2005 6:21 AM
	To: ibis-users@eda.org; ibis@eda.org
	Subject: [IBIS] Differential Buffer Modelling

	IBIS Gurus,

	 

	I have some questions about generating differential buffer model as stated in latest Cookbook 4.0.

	1)          My normalized differential mode current has a similar plot as shown in Pg 36. It's a function of the differential voltage, so that makes the usage of keyword [Series Current] appropriate in this case. To fill the I-V table, am I supposed to use the Vdiff vs Idiff ?

	2)          For the V-T table data extraction, it was mentioned in Pg 40 that for [Series Current] keyword, PWL current source can be used to replace the R value. What should be the PWL response to represent the Idiff? (Idiff was only found to be a function of Vdiff from I-V extraction). 

	 

	Please advise if my assumptions are incorrect.  

	 

	Thanks

	Kong-Yew


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