So many reference guides insist that there should be no power split while routing high speed signals, and many engineers regard it as the bible. Of course, intact reference plane is perfect but it is not always available. You have to balance the performance and cost and other things. Hence, SI engineers need to be care of their stackup design and decide whether or where stitching capacitor needed or something else. All depends on how much you can rely on your design. Benny Yan IO Methodology Inc From: zhangchh@xxxxxxxxxx [mailto:zhangchh@xxxxxxxxxx] Sent: Thursday, August 30, 2007 2:26 PM To: zyan@xxxxxxxxxx Cc: m_p_sen@xxxxxxxxx; si-list@xxxxxxxxxxxxx; si-list-bounce@xxxxxxxxxxxxx Subject: ç?å¤?: [SI-LIST] Re: return path No permission that High-speed signalï¼?CLKï¼?DDR ...ï¼?'s mirror plane have so many splits. Any problem, pls let me know. Thanks ! Efficiency & Innovation **************************************************** **************************************************** "Benny Yan" <zyan@xxxxxxxxxx> å??件人ï¼? si-list-bounce@xxxxxxxxxxxxx 2007/08/30 14:09 请ç?å¤? ç»? zyan æ?¶ä»¶äººï¼? <m_p_sen@xxxxxxxxx> æ??é??ï¼? <si-list@xxxxxxxxxxxxx> 主é¢?ï¼? [SI-LIST] Re: return path It does not sound a good idea with many split, while It depends on the = speed of your signals. For asymmetric stripline, the distance proportion to ground and power = plane should be concerned. Benny Yan IO Methodology Inc. -----Original Message----- From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] = On Behalf Of sengottuvel m.p. Sent: Thursday, August 30, 2007 1:16 PM To: tbiggs@xxxxxxxxxxxxxxxxxxxxx; si-list@xxxxxxxxxxxxx Subject: [SI-LIST] Re: return path Hi all, =20 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? =20 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.=3D20 --------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.=3D20 And on the downside: 3. More EMI=3D20 4. More crosstalk (for a given spacing of traces). 3. Tarnishing How does tarnishing affect the signal?=3D20 -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=3D20 > [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=3D20 > 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: =3D3D20 > //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 > =3D3D20 > ------------------------------------------------------------------ > 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 > > > =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: =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 = _________________________________________________________________________= ___________ Luggage? 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Search http://search.yahoo.com/search?fr=3Doni_on_mail&p=3Dgraduation+gifts&cs=3D= 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: =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 ------------------------------------------------------------------ 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