[SI-LIST] Re: risetime effects of plane breaks
- From: Doug Smith <doug@xxxxxxxxxx>
- To: Chris.Cheng@xxxxxxxxxxxx
- Date: Fri, 14 Jan 2005 15:23:30 -0800
Hi Chris,
I agree with you, but I have lost count of how many times I have seen
this done, even in high speed designs. I call this income enhancement
for consultants.
Doug
Chris Cheng wrote:
> Sorry but I have to ask, why would anyone will run a single edge signal at
> 300ps as microstrip across a cut ground reference plane ? I can understand
> if it is a stripline with a solid ground on one reference and cut power
> planes on the other (which I have do a lot, not by choice though). What
> application will call for such routing ?
>
> -----Original Message-----
> From: steve weir [mailto:weirsp@xxxxxxxxxx]
> Sent: Monday, January 10, 2005 12:28 PM
> To: arpad.muranyi@xxxxxxxxx; SI-List
> Subject: [SI-LIST] Re: risetime effects of plane breaks
>
>
> Arpad, a jump from 10-14% coupling up to 30% or so is still very
> significant. Phase match and other common mode issues should not be
> dismissed when attempting to cross a split. The first choice should be
> don't do it. But if one must, then do so with care.
>
> Regards,
>
>
> Steve.
> At 11:41 AM 1/10/2005 -0800, Muranyi, Arpad wrote:
>
>>Even though I was just speed reading this
>>thread, I didn't see this mentioned yet:
>>
>>You can also get by with plane breaks if the
>>traces going over it are closely coupled
>>differential pairs...
>>
>>Arpad
>>=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
>
> =
>
>>=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=20
>>
>>-----Original Message-----
>>From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] =
>>On Behalf Of steve weir
>>Sent: Monday, January 10, 2005 11:21 AM
>>To: emcesd2000@xxxxxxxxx; SI-List
>>Subject: [SI-LIST] Re: risetime effects of plane breaks
>>
>>Oscar, yes, it is quite a dramatic effect isn't it? I suspect that =
>>when=20
>>Lee says "it depends on how you do it" he has another contiguous plane, =
>>ie=20
>>ground underneath the split as opposed to a split on all planes as in=20
>>Doug's experiment. Assuming lots of decoupling between each of the =
>>islands=20
>>and the common ground plane the jump in coupling between lines would be =
>>
>>greatly suppressed.
>>
>>Regards,
>>
>>
>>Steve.
>>
>>At 11:00 AM 1/10/2005 -0800, Ahmad Fallah wrote:
>>
>>>Hi Steve,
>>>
>>>I have repeated Doug's experiment with a modified fixture where an=20
>>>additional trace (victim) was added near (~1 cm) the "signal" line for=20
>>>X-talk measurements. I have measured a 10-fold increase in x-talk=20
>>>amplitude in going from Case 1 to Case 2.
>>>
>>>Case 1: the offending and victim lines are both drawn over a solid =
>>
>>return=20
>>
>>>plane.
>>>Case 2: the offending and victim lines are both drawn over the cut in =
>>
>>the=20
>>
>>>return plane
>>>
>>>Regards,
>>>
>>>Oscar
>>>
>>>
>>>
>>>steve weir <weirsp@xxxxxxxxxx> wrote:
>>>
>>>Lee, the 5cm is the length of the break. The break is only about =
>>
>>20-50mils
>>
>>>wide. Hit the link and scroll to Figure 3. In Doug's test set-up, both =
>>
>>of
>>
>>>the two planes have been broken. Now, If one cares to do a crosstalk =
>>
>>test,
>>
>>>it looks like Doug could modify his fixture rather easily to do that. =
>>
>>In
>>
>>>the vicinity of the break, the multiple line coupling, including =
>>
>>between
>>
>>>members of a diff pair jumps.
>>>
>>>
>>>
>>>
>>>
>>>If you want to perform an entertaining experiment, take a diff pair, or
>>>just one active driver and a quiet line and route them over a narrow, =
>>
>>and
>>
>>>short break, say 0.25" by 0.02" and take four port S parameter
>>>measurements. Take another pair and do likewise, but keep extending the
>>>length of the slot, ie perpendicular to the traces by a factor of 2 =
>>
>>with
>>
>>>each test. Even though the width of the gap is short, by the time that
>>>slot becomes an inch or two long the band of frequencies where coupling =
>>
>>is
>>
>>>fairly strong will be pretty wide.
>>>
>>>http://emcesd.com/tt2005/tt010105.htm
>>>
>>>Regards,
>>>
>>>Steve
>>>
>>>
>>>At 04:30 PM 1/9/2005 -0800, Lee Ritchey wrote:
>>>
>>>>Just noticed that you call a 5 cm break relatively small. Does that =
>>
>>mean
>>
>>>>5 cm in width?
>>>>
>>>>Lee W. Ritchey
>>>>Speeding Edge
>>>>P. O. Box 2194
>>>>Glen Ellen, CA 95442
>>>>Phone- 707-568-3983
>>>>FAX- 707-568-3504
>>>>
>>>>I just used the energy it took to be angry to write some blues.
>>>>Count Basie
>>>>
>>>>
>>>>
>>>>>[Original Message]
>>>>>From: Doug Smith
>>>>>To: SI-List
>>>>>Date: 1/8/2005 5:23:26 PM
>>>>>Subject: [SI-LIST] risetime effects of plane breaks
>>>>>
>>>>>I think most of us know not to route signals over plane breaks on =
>>
>>PWBs
>>
>>>>>as all kinds of bad things can happen when this occurs in a =
>>
>>layout.
>>
>>>>>But, how do you convince co-workers or your boss that a new design
>>>>>needs to avoid doing this even if added expense or project delay =
>>
>>is
>>
>>>>>required? Experimental data can be the key and this month my =
>>
>>Technical
>>
>>>>>Tidbit shows what happens to signal risetime if the signal crosses =
>>
>>a
>>
>>>>>plane break.
>>>>>
>>>>>Crossing Ground Plane Breaks - Part 4
>>>>>Risetime Effects on Signals
>>>>>
>>>>>Abstract: Signals that cross ground plane breaks on printed wiring
>>>>>boards (PWBs) experience degradation as well as cause EMI =
>>
>>problems.
>>
>>>>>Significant degradation of signal risetime is shown to occur, even
>>>>>with a relatively small ground break of five cm at risetimes on =
>>
>>the
>>
>>>>>order of 300 ps.
>>>>>
>>>>>The link to the article is the picture of the experimental test =
>>
>>setup
>>
>>>>>at the bottom of the home page at http://emcesd.com .
>>>>>
>>>>>Doug
>>>>>--
>>>>>-------------------------------------------------------
>>>>>___ _ Doug Smith
>>>>>\ / ) P.O. Box 1457
>>>>>=3D=3D=3D=3D=3D=3D=3D=3D=3D Los Gatos, CA 95031-1457
>>>>>_ / \ / \ _ TEL/FAX: 408-356-4186/358-3799
>>>>>/ /\ \ ] / /\ \ Mobile: 408-858-4528
>>>>>| q-----( ) | o | Email: doug@xxxxxxxxxx
>>>>>\ _ / ] \ _ / Website: http://www.dsmith.org
>>>>>-------------------------------------------------------
>>>>>
>>>>>------------------------------------------------------------------
>>>>>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
>>>>
>>>
>>>
>>>------------------------------------------------------------------
>>>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
>>>
>>
>>
>>------------------------------------------------------------------
>>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: =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 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
>
> ------------------------------------------------------------------
> 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
>
>
>
>
--
------------------------------------------------------------
___ _ Doug Smith
\ / ) P.O. Box 1457
========= Los Gatos, CA 95031-1457
_ / \ / \ _ TEL/FAX: 408-356-4186/358-3799
/ /\ \ ] / /\ \ Mobile: 408-858-4528
| q-----( ) | o | Email: doug@xxxxxxxxxx
\ _ / ] \ _ / Web: http://www.dsmith.org
------------------------------------------------------------
------------------------------------------------------------------
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:
