[SI-LIST] Re: Differential Impedance of PCB Vias
- From: "Ing. Giancarlo Guida" <gianguida@xxxxxxxx>
- To: Hirshtal Itzhak <ihirshtal@xxxxxxxxxx>
- Date: Wed, 15 Feb 2006 09:23:47 +0100
Itzhak,
it would be very nice to have a simple formula
also for complicated structure...but as you are experiencing
this is not always possible.
But there other good reasons to justify the effort
to model a differential via by using a 3D solver:
1) you could make a parametric model and have a look on what
really matter in the behavior of your via
i.e you may have a look inside the physics of your problem
2) once you have done it you can re-use the via model
for several different design
3) even you will find a formula that will help you today
you will need a 3D solver tomorrow when you data-rate will be higher...
so may be it is good idea jump on simulator ship today...:-)))
Regards
Giancarlo
Hirshtal Itzhak ha scritto:
> Hello Giancarlo,
>
> Instead of simulating in 3D, I assume that in my case I can live with
> approximate values, so for evaluating the parasitics and impedance of
> vias I am now using H. Johnson's empirical tables appearing on his
> advanced SI book. The problem is - the differential impedance has not
> been addressed there, and I wonder if there maybe exist some similar
> empirical data regarding differential vias!
>
>
> Itzhak hirshtal
>
> -----Original Message-----
> From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx]
> On Behalf Of Ing. Giancarlo Guida
> Sent: Monday, February 13, 2006 3:34 PM
> To: Hirshtal Itzhak
> Cc: si-list@xxxxxxxxxxxxx
> Subject: [SI-LIST] Re: Differential Impedance of PCB Vias
>
> Hi Itzhak,
> in your case
> you should take in thye account the overall layout of the via:
> pad and antipad dimension,
> via radius
> presence of stub
> via to ground
>
> I doubt you can do this efficiently by using a formula you would be in a
> better shape if you could use a 3D solver to find the best layout for
> your via.
>
> I am using CST Microwave studio for such a problem and I find it very
> efficient.
>
> Giancarlo
>
> Hirshtal Itzhak ha scritto:
>
>>
>> Hello,
>>
>> I need to route a 3.125Gb/s 100-ohm diff pair such that it traverses
>> from one layer of a PCB to another layer through a pair of vias about
>> 100mil long.
>>
>> I would like to keep the diff impedance of the pair of vias as close
>> to 100-ohm as possible.
>>
>> How can I estimate the diff impedance of the vias? Is there a reliable
>>
>
>
>> formula to calculate this value out of the self characteristic
>> impedance of the vias or from their geometrical dimensions?
>>
>> Thanks for anyone who can contribute
>>
>> Itzhak Hirshtal
>> Elta Electronics
>> Israel
>>
>>
>>
>> The information contained in this communication is proprietary to
>>
> Israel Aircraft Industries Ltd.
>
>> and/or third parties, may contain confidential or privileged
>> information, and is intended only for the use of the intended
>> addressee thereof. If you are not the intended addressee, please be
>>
> aware that any use, disclosure, distribution and/or copying of this
> communication is strictly prohibited.
>
>> If you receive this communication in error, please notify the sender
>> immediately and delete it from your computer. Thank you.
>>
>>
>> This message is processed by the PrivaWall Email Security Server.
>>
>>
>>
>> ------------------------------------------------------------------
>> To unsubscribe from si-list:
>> si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field
>>
>> or to administer your membership from a web page, go to:
>> //www.freelists.org/webpage/si-list
>>
>> For help:
>> si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field
>>
>> List FAQ wiki page is located at:
>> http://si-list.org/wiki/wiki.pl?Si-List_FAQ
>>
>> List technical documents are available at:
>> http://www.si-list.org
>>
>> List archives are viewable at:
>> //www.freelists.org/archives/si-list
>> or at our remote archives:
>> http://groups.yahoo.com/group/si-list/messages
>> Old (prior to June 6, 2001) list archives are viewable at:
>> http://www.qsl.net/wb6tpu
>>
>>
>>
>>
>>
>>
>
>
> ------------------------------------------------------------------
> To unsubscribe from si-list:
> si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field
>
> or to administer your membership from a web page, go to:
> //www.freelists.org/webpage/si-list
>
> For help:
> si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field
>
> List FAQ wiki page is located at:
> http://si-list.org/wiki/wiki.pl?Si-List_FAQ
>
> List technical documents are available at:
> http://www.si-list.org
>
> List archives are viewable at:
> //www.freelists.org/archives/si-list
> or at our remote archives:
> http://groups.yahoo.com/group/si-list/messages
> Old (prior to June 6, 2001) list archives are viewable at:
> http://www.qsl.net/wb6tpu
>
>
>
>
> This message is processed by the PrivaWall Email Security Server.
>
>
>
>
>
> The information contained in this communication is proprietary to Israel
> Aircraft Industries Ltd.
> and/or third parties, may contain confidential or privileged information, and
> is intended only for
> the use of the intended addressee thereof. If you are not the intended
> addressee, please be aware
> that any use, disclosure, distribution and/or copying of this communication
> is strictly prohibited.
> If you receive this communication in error, please notify the sender
> immediately and delete it from
> your computer. Thank you.
>
>
> This message is processed by the PrivaWall Email Security Server.
>
>
>
>
>
------------------------------------------------------------------
To unsubscribe from si-list:
si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field
or to administer your membership from a web page, go to:
//www.freelists.org/webpage/si-list
For help:
si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field
List FAQ wiki page is located at:
http://si-list.org/wiki/wiki.pl?Si-List_FAQ
List technical documents are available at:
http://www.si-list.org
List archives are viewable at:
//www.freelists.org/archives/si-list
or at our remote archives:
http://groups.yahoo.com/group/si-list/messages
Old (prior to June 6, 2001) list archives are viewable at:
http://www.qsl.net/wb6tpu
Other related posts:
