[SI-LIST] Re: Seperate Sparameter for gnd & supply plane !!

  • From: steve weir <weirsi@xxxxxxxxxx>
  • To: Rajesh K <rajeshk0212@xxxxxxxxx>
  • Date: Thu, 02 Jun 2011 18:51:07 -0700

Define a port across the two points where you want to determine the 
potential difference.  Extract S11.

Steve.
On 6/2/2011 6:18 PM, Rajesh K wrote:
> you are very much correct, one VDD or ten VDD doesn't matter. it all matters
> potential difference. This is universal truth, we are not debating here this
> point. The question is, how should I get or generate separate s-parameter
> for VDD, VSS domain in a typical die, package, pcb connected system. This is
> purely from simulation point of view. I wish to probe(in simulation) VSS
> noise at different point in package, pcb, die input. if I use typical
> s-parameter, VSS of package, pcb&  die will be lumped together. Therefore, I
> will not be able to estimate VSS noise at different point.
> please do not expect to write new EM tool which will need to search for
> equipotential point. suggest some solution within existing set of EM tools
> available in market
> On Fri, Jun 3, 2011 at 6:28 AM, steve weir<weirsi@xxxxxxxxxx>  wrote:
>
>> **
>> One Vdd, or ten Vdd's, does not matter.  AC and DC current will result in
>> voltage potentials through interconnects.  Vss at any two points on a die,
>> PCB plane, or different planes in a stack-up will have different absolute
>> potentials.  The issue is:  you need to understand what that potential
>> difference is in reference to, or perhaps more importantly, what it is
>> common to, and therefore whether it matters.  If you were to probe a given
>> signal or power rail, think about where would you ideally put the ground
>> side of your scope probe, and why you would put it there.
>>
>> Steve.
>>
>>
>> On 6/2/2011 5:11 PM, Rajesh K wrote:
>>
>> in a system with multi-voltage power rail, where VSS is common to all the
>> power rails. any noise on VSS will impact system performance differently.
>> you will get different results if you assume VSS quiet/noisy. separate
>> s-parameters of power&  VSS are highly desirable in such scenario.
>>
>>
>> --
>> Thanks
>> Rajesh
>>
>>
>>
>> --
>> Steve Weir
>> IPBLOX, LLC
>> 150 N. Center St. #211
>> Reno, NV  89501 www.ipblox.com
>>
>> (775) 299-4236 Business
>> (866) 675-4630 Toll-free
>> (707) 780-1951 Fax
>>
>>
>>
>


-- 
Steve Weir
IPBLOX, LLC
150 N. Center St. #211
Reno, NV  89501
www.ipblox.com

(775) 299-4236 Business
(866) 675-4630 Toll-free
(707) 780-1951 Fax


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