[SI-LIST] Re: Maximum Frequency for S-parameter Extraction of Board Power Plane

  • From: "Beal, Weston" <Weston_Beal@xxxxxxxxxx>
  • To: Rajan Hansa <all.si.list@xxxxxxxxx>, "si-list@xxxxxxxxxxxxx" <si-list@xxxxxxxxxxxxx>
  • Date: Wed, 18 May 2011 16:32:22 +0000

Make sure that you consider not only the maximum frequency. You also need to 
make sure that your S-parameter set has enough data points to correctly model 
all the resonances in the measured frequency band. If you have too few data 
points, and the graph of the S-parameters over frequency looks choppy or 
jagged, then the model will probably be non-causal.

S-parameters are like power tools. A skilled user can get a lot done with them, 
but if used carelessly, they can hurt you.

Weston


-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On 
Behalf Of Rajan Hansa
Sent: Wednesday, May 18, 2011 3:44 AM
To: si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Maximum Frequency for S-parameter Extraction of Board Power 
Plane

Hello All,


I have got a PCB database of one Ethernet Board and I have to extract 
s-parameter for all power plane from voltage regulator to  power pin of chip 
package. The Board database includes all decap.



As we know extraction time is directly related with maximum frequency So while 
setting maximum frequency for s-parameter extraction, I am bit confused, I 
would like to know that do I need to set knee frequency ( Fknee = 0.35/Trise) 
as maximum frequency OR for board level simulation we shouldn't care knee 
frequency.



As per my understanding, package inductance won't allow very high frequency 
component (switching current component which depends on Trise !!) to travel to 
board from chip so voltage regulator in board will never see those high 
switching current so I shouldn't simulate/extract s-parameter till knee 
frequency.



What's expert view on this ?



Rgds,

Rajan

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