[SI-LIST] Re: return path

  • From: steve weir <weirsi@xxxxxxxxxx>
  • To: m_p_sen@xxxxxxxxx
  • Date: Wed, 29 Aug 2007 23:03:40 -0700

m. p.  it depends on how much you want and can rely on the PDN to 
maintain return path continuity across those splits.  In the end the 
answer is not yes or no but a matter of numbers. 

Steve
sengottuvel m.p. wrote:
> Hi all,
>  
> When we have stripline trace between power and ground plane with many split 
> in power and full plane in ground, is it ok the good return path  through 
> ground? or asymmetric stripline i.e. trace near ground is preferable?
>  
> Thanks,
> Sengo
>
> ----- Original Message ----
> From: Tom Biggs <tbiggs@xxxxxxxxxxxxxxxxxxxxx>
> To: si-list@xxxxxxxxxxxxx
> Sent: Thursday, August 30, 2007 4:31:08 AM
> Subject: [SI-LIST] Re: Conductor loss reduction at High Frequency
>
>
> There are three things mentioned in this thread that caught my interest:
>
> 1. trace/trace core versus trace/power core
>
> Assume that you have two layers around a core. I assume that the side of
> a trace next to the center of the core is rougher than the side on the
> outside of the core.
>
> Given a nonsymmetrical stripline, more of the current is going to travel
> on the side of the trace closest to the nearest ground/power plane.=20
> --------power
> --  trace
> --  trace
> --------power
>
> If the core is between the trace layers, then the side of the trace
> closest to the power plane will be smooth. If the core is between
> trace/power layers, then this side of the trace is going to be rough.
> You would expect lower loss in the trace/trace core case. True?
>
> 2. Surface layers
> It was mentioned that with microstrip surface layers that your
> impendence is not as well controlled, presumably because the surface
> layer is a foil layer so its distance to the next plane layer is not
> well controlled, since it is determined by the final press of all
> layers, and can vary from build to build.
>
> But, if you use surface layers, you can widen your trace by using more
> prepreg layers, giving you:
> 1. Lower loss (at least for short lengths)
> 2. It is easier to control the trace thickness and height within a
> certain # of mils if the trace is thicker and higher, so if the trace is
> thick enough it should be easy to control its impendence, even on an
> outer layer. E.g. 12 mils +/- 1 mil has a much tighter impendence
> control than 3 mils +/- 1 mil.
> I'm not sure if this is enough to compensate for the poor height
> control.=20
> And on the downside:
> 3. More EMI=20
> 4. More crosstalk (for a given spacing of traces).
>
> 3. Tarnishing
> How does tarnishing affect the signal?=20
>
>    -tom
>
> -----Original Message-----
> From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx]
> On Behalf Of Scott McMorrow
> Sent: Wednesday, August 29, 2007 2:11 PM
> To: jeff.loyer@xxxxxxxxx
> Cc: sridharam@xxxxxxxxxx; si-list@xxxxxxxxxxxxx
> Subject: [SI-LIST] Re: Conductor loss reduction at High Frequency
>
> Surface roughness is the largest contributor we've measured for
> conductor loss.  There are certain low loss materials that are
> constructed with high tooth copper for maximum adhesion, which show
> enough loss to absolutely negate any benefit that the low loss (low tan
> delta) material would have had over materials with twice the dielectric
> loss.
>
> Interesting stuff.
>
> Scott McMorrow
> Teraspeed Consulting Group LLC
> 121 North River Drive
> Narragansett, RI 02882
> (401) 284-1827 Business
> (401) 284-1840 Fax
>
> http://www.teraspeed.com
>
> Teraspeed(r) is the registered service mark of Teraspeed Consulting
> Group LLC
>
>
>
> Loyer, Jeff wrote:
>   
>> My 2 cents available in the article below:
>>
>> http://pcdandm.com/cms/content/view/2572/95/
>>
>>
>> Jeff Loyer
>>
>> -----Original Message-----
>> From: si-list-bounce@xxxxxxxxxxxxx=20
>> [mailto:si-list-bounce@xxxxxxxxxxxxx]
>> On Behalf Of M Sridhar
>> Sent: Wednesday, August 29, 2007 5:08 AM
>> To: si-list@xxxxxxxxxxxxx
>> Subject: [SI-LIST] Conductor loss reduction at High Frequency
>>
>> Hi Members,
>>
>> What are the methods by which we can reduce the conductor losses at=20
>> high frequency?(Loss due to skin effect, Dielectric losses etc.) Which
>>     
>
>   
>> is the best conductor at higher frequency? in the range of 1-5 GHz
>>
>> Thanks,
>> Sridhar
>> ------------------------------------------------------------------
>> 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 technical documents are available at:
>>                 http://www.si-list.net
>>
>> List archives are viewable at:    =3D20
>>         //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
>>  =3D20
>> ------------------------------------------------------------------
>> 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 technical documents are available at:
>>                 http://www.si-list.net
>>
>> List archives are viewable at:    =20
>>         //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
>>  =20
>>
>>
>>  =20
>>     
> ------------------------------------------------------------------
> 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 technical documents are available at:
>                 http://www.si-list.net
>
> List archives are viewable at:    =20
>         //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
> =20
> ------------------------------------------------------------------
> 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 technical documents are available at:
>                 http://www.si-list.net
>
> 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
>
>
>       
> ____________________________________________________________________________________
> Luggage? GPS? Comic books? 
> Check out fitting gifts for grads at Yahoo! Search
> http://search.yahoo.com/search?fr=oni_on_mail&p=graduation+gifts&cs=bz
> ------------------------------------------------------------------
> 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 technical documents are available at:
>                 http://www.si-list.net
>
> 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
>   
>
>
>
>   


-- 
Steve Weir
Teraspeed Consulting Group LLC 
121 North River Drive 
Narragansett, RI 02882 

California office
(408) 884-3985 Business
(707) 780-1951 Fax

Main office
(401) 284-1827 Business 
(401) 284-1840 Fax 

Oregon office
(503) 430-1065 Business
(503) 430-1285 Fax

http://www.teraspeed.com
This e-mail contains proprietary and confidential intellectual property of 
Teraspeed Consulting Group LLC
------------------------------------------------------------------------------------------------------
Teraspeed(R) is the registered service mark of Teraspeed Consulting Group LLC

------------------------------------------------------------------
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 technical documents are available at:
                http://www.si-list.net

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: