Re: [IBIS-Users] Differential Buffer Modelling

From: Paul Fernando <Paul.Fernando_at_.....>
Date: Tue Oct 04 2005 - 12:04:54 PDT

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

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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

 

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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

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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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