[SI-LIST] Re: PDS target Impedance (adaptive method)

Hi Lakshmi,

The impedance profile can be obtained from the noise tolerance vs. frequency 
which should be a matter of the chip vendor. Thus I suggest to ask the vendor 
first to provide the "target impedance" profile.
Although the formula may give the "worst-case" target, it should be 
over-estimated. So you need to know which frequency component may affect the 
chip.

Regards,
----
Tadashi ARAI / SMTS Hardware Support Engineer
Platform Engineering, Customer Support Services
Japan Engineering Lab., AMD Japan Limited 

-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On 
Behalf Of Alexandre.AMEDEO@xxxxxxxxxxxxxxxxxx
Sent: Friday, February 20, 2009 11:02 PM
To: imsong91@xxxxxxxxx; lakshminarayanans@xxxxxx
Cc: si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Re: PDS target Impedance (adaptive method)

Hi Lakshmi, 

I would like to know, how do you do to define target impedance with ibis model?
Thanks and Regards, 

Alexandre AMEDEO

-----Message d'origine-----
De : si-list-bounce@xxxxxxxxxxxxx
[mailto:si-list-bounce@xxxxxxxxxxxxx]De la part de Inmyoung Song Envoyé : 
vendredi 20 février 2009 08:08 À : Lakshmi Narayanan Sowrirajan, TLS-Chennai Cc 
: si-list@xxxxxxxxxxxxx Objet : [SI-LIST] Re: PDS target Impedance (adaptive 
method)


If I want to get the target impedance based on frequency, I do simulation with 
ibis model.
Every spice simulator can show the current result during operating, so we can 
get the target impedance.
Many engineers have a rule of thumb where all data bits operate simultaneously 
or randomly.
Good luck!
2009/2/13 Lakshmi Narayanan Sowrirajan, TLS-Chennai < lakshminarayanans@xxxxxx>

> Hi,
>
>
>
>            I am working in PDS analysis. Can you please explain me on 
> fixing the target impedance of the power distribution network?
>
> The general formula gives
>
>
>
>            Z (target) = (Supply Voltage * Ripple Tolerance) / Dynamic 
> current
>
>
>
> This formula is not considering the frequency effect as over some 
> frequency the target impedance can be varying (going high). How to 
> account for this in the analysis?
>
>
>
> Thanks & Regards
>
> Lakshminarayanan.S
>
> 9840250902
>
>
>
>
>
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--
Signal Integrity Engineer
South Korea


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