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

On 5/19/2011 4:28 AM, Rohit MISHRA wrote:
> Steve,
>
> Why do you think you can ignore the package in the frequency ranges that you 
> consider the PCB for power delivery?
>
> I think I was wrong for minimum frequency, As PCB power plane is basically a 
> low pass filter so package will also see all low frequency components down to 
> 0 Hz, right ?
Yes, the package is in series with the PCB.
> Why do you think that Fknee is the highest frequency you need to consider?
>
> Fknee (0.35/Trise) is the maximum frequency where most of the energy of the 
> signal exist so we should care bandwidth till knee frequency.
>
> This is my understanding, I may be wrong but nevertheless I would love to 
> hear your views.
If you only care about the transmission path for one signal, Fknee gives 
an APPROXIMATE bandwidth beyond which arbitrary channel response will 
not introduce MUCH signal distortion.   Parallel lots of signals and 
even though each signal has only a small percentage power beyond Fknee, 
the total power beyond Fknee can be substantial and make a very 
effective radio transmitter.
> Rohit
>
>
>
> -----Original Message-----
> From: steve weir [mailto:weirsi@xxxxxxxxxx]
> Sent: Thursday, May 19, 2011 1:56 PM
> To: Rohit MISHRA
> Cc: si-list@xxxxxxxxxxxxx; Muranyi, Arpad
> Subject: Re: [SI-LIST] Re: Maximum Frequency for S-parameter Extraction of 
> Board Power Plane
>
> Why do you think you can ignore the package in the frequency ranges that
> you consider the PCB for power delivery?
> Why do you think that Fknee is the highest frequency you need to consider?
>
> Steve.
> On 5/19/2011 12:26 AM, Rohit MISHRA wrote:
>> Guys,
>>
>> Interesting discussion, Indeed !!
>>
>> Now in case if we extract power plane s-parameter for package, what would be 
>> the minimum&   maximum frequency ??
>>
>> As per my understanding :
>>
>> Minimum frequency = 3 X cut off frequency of board
>> Maximum Frequency = Knee frequency
>>
>> Experts comments please.
>>
>> Rohit
>>
>>
>>
>>
>> -----Original Message-----
>> From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On 
>> Behalf Of Muranyi, Arpad
>> Sent: Wednesday, May 18, 2011 10:12 PM
>> To: si-list@xxxxxxxxxxxxx
>> Subject: [SI-LIST] Re: Maximum Frequency for S-parameter Extraction of Board 
>> Power Plane
>>
>> I might add that one has to make sure that the S-parameter data
>> goes down low enough in frequency, preferably to 0 Hz, otherwise
>> the simulators will have to guess on how to solve for the DC
>> components of the signal...  Based on the "your guess is as good
>> as mine" principle your results may vary...
>>
>> Arpad
>> ==================================================================
>>
>> -----Original Message-----
>> From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx]
>> On Behalf Of Beal, Weston
>> Sent: Wednesday, May 18, 2011 11:32 AM
>> To: Rajan Hansa; si-list@xxxxxxxxxxxxx
>> Subject: [SI-LIST] Re: Maximum Frequency for S-parameter Extraction of
>> Board Power Plane
>>
>> 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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