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

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> 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> 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
>>
>> (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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