[SI-LIST] Re: Seperate Sparameter for gnd & supply plane !!
- From: steve weir <weirsi@xxxxxxxxxx>
- To: Rajan Hansa <all.si.list@xxxxxxxxx>
- Date: Wed, 01 Jun 2011 04:33:59 -0700
Don't suppose. Analyze. Your real problem is that you analog engineer
wants to understand the extent of noise disturbance that is associated
with the interconnects and PDN. He first needs to define his problem by
deciding for each victim what location in the assembly constitutes his
reference. Once that is done, the problem can be solved with analytical
tools. An equipotential if it exists somewhere convenient reduces the
effort required to get a reasonable answer.
Steve
On 6/1/2011 4:23 AM, Rajan Hansa wrote:
>
> Steve,
>
> The board has many chips including ours and they all have different
> current requirement so it won't be correct to consider it
> equipotential and if I suppose consider them quasi-equipotential, what
> extra things I have to take care while generating s-parameter ?? OR do
> you mean to say for quasi-equipotential, separate vdd & gnd
> s-parameters will take care our problem ?
>
> Rajan
>
> On Wed, Jun 1, 2011 at 4:10 PM, steve weir <weirsi@xxxxxxxxxx
> <mailto:weirsi@xxxxxxxxxx>> wrote:
>
> You have a matrix of current sources attached to a matrix of RLCG
> legs, and you want to know the noise voltage that occurs between
> different point pairs in that matrix. If the product of the
> static and dynamic currents against a section of those legs is
> very small, you can treat that region as a quasi- equipotential.
> Otherwise you have to treat the point pairs as unique.
>
> Steve
>
>
> On 6/1/2011 3:29 AM, Rajan Hansa wrote:
>>
>> Steve,
>>
>> You are right !! Our analog engineer basically wants to
>> see ground bounce w.r.t pcb ground which was not possible with
>> single s-parameter but you said that I have to do whole lot more
>> than just produce s-parameters between one port inside the
>> package and some other virtual port.
>>
>> Can you help me to understand that why separate s-parameter is
>> not sufficient to see ground bounce and what is the right way to
>> handle such problems ??
>> Rajan
>>
>>
>> On Wed, Jun 1, 2011 at 3:30 PM, steve weir <weirsi@xxxxxxxxxx
>> <mailto:weirsi@xxxxxxxxxx>> wrote:
>>
>> What it sounds like your analog engineer wants is to be able
>> to figure out how much bounce will occur in each plane
>> relative to some external reference, such as the PCB Vss
>> plane. In order to figure that out, you have to do a whole
>> lot more than just produce s-parameters between one port
>> inside the package and some other virtual port. Your analog
>> engineer needs to be more specific about what he wants to
>> figure out.
>>
>> Steve.
>>
>>
>> On 6/1/2011 1:41 AM, Rajan Hansa wrote:
>>
>> Guys,
>> I have got a request to provide sparameter for one
>> package but this time my
>> analog engineer wants seperate s-parameter for gnd&
>> supply plane. The
>> reason he gave is that with single sparameter for vdd&
>> gnd plane. He can't
>> see gnd noise as s-parameter is generated with gnd as
>> reference so it'll
>> always be seen as '0' but that problem won't come in
>> separate s-parameters
>> for gnd& supply planes.
>>
>> Though the tool I am using has an option to generate
>> sparameter with
>> reference to some virtual point and I can use that option
>> to generate
>> separate sparameters for gnd& supply but problem is that
>> I have not still
>> understood if using separate s-parameter is a right way
>> to do things and if
>> it's the standard practice in industry.
>>
>> Experts comments please.
>>
>> Rajan
>>
>>
>>
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>>
>>
>> --
>> Steve Weir
>> IPBLOX, LLC
>> 150 N. Center St. #211
>> Reno, NV 89501
>> www.ipblox.com <http://www.ipblox.com/>
>>
>> (775) 299-4236 Business
>> (866) 675-4630 Toll-free
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>>
>>
>>
>
>
> --
> Steve Weir
> IPBLOX, LLC
> 150 N. Center St. #211
> Reno, NV 89501
> www.ipblox.com <http://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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