Hello. If anyone is interested in putting 100 ohm differential shielded cables ( also ribbonized ) and connectors on backplane for 3.125gb/s signaling please let me know. I have the solution in a PDF file on my computer ready to go. Put the sensitive signals on small minature differential coax cable and zip the problem is solved. Run them 3 feet long if you want no problem. Go Board to connector to differential cable to connector and back to board. It works great. Richard Jungert > Date: Mon, 15 Sep 2008 14:45:19 -0400 > From: scott@xxxxxxxxxxxxx > To: vinu@xxxxxxxxx > CC: leeritchey@xxxxxxxxxxxxx; mrose@xxxxxxxxxxxx; si-list@xxxxxxxxxxxxx > Subject: [SI-LIST] Re: plane-to-plane decoupling > > Vinu > Not quite. As long as there is a ground plane underneath, and close to, > the capacitor, some return path energy will get across. But, there is a > mismatch in impedance between the capacitor and plane, and here is still > an inductive loop for the return energy to get to the capacitor. > Because of this, quite a bit of the common mode energy will be reflected > back into the near end power/ground plane cavity. > > regards, > > Scott > > 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® is the registered service mark of > Teraspeed Consulting Group LLC > > > > Vinu Arumugham wrote: > > Lee, > > The capacitor used for AC coupling on the signal path, should be able > > work just as good if it were placed on the return path as a decoupling > > capacitor for that signal. > > Each signal trace will of course need a dedicated capacitor to avoid > > additional crosstalk. > > > > Thanks, > > Vinu > > > > Lee Ritchey wrote: > > > >> Michael, > >> > >> There are no capacitors that work at 3.125 Gb/S for decoupling. The way to > >> provide this path is by placing the planes close to each other. I use 3 > >> mils all of the time for this purpose. Works greast! > >> > >> Lee Ritchey > >> Speeding Edge > >> > >> > >> > >> > >>> [Original Message] > >>> From: Michael Rose <mrose@xxxxxxxxxxxx> > >>> To: SI-List <si-list@xxxxxxxxxxxxx> > >>> Date: 9/15/2008 10:01:17 AM > >>> Subject: [SI-LIST] plane-to-plane decoupling > >>> > >>> I looking for some suggestions regarding decoupling between co-planar > >>> plane splits. I'm working on a backplane with a number of 3.125Gbps diff > >>> pairs. I've specified a dual stripline stackup assigned as follows: > >>> > >>> 1 - P > >>> 2 - G > >>> 3 - S > >>> 4 - S > >>> 5 - P > >>> 6 - G > >>> and so on > >>> > >>> Some diff pairs on L4 will cross power plane splits (actual different > >>> power sources and loads) and I wanted to provide an effective AC path > >>> for any common-mode return currents. I was thinking about placing some > >>> nearby decoupling caps from plane-to-plane across the split. Do you > >>> think it would be better to decouple from plane-to-ground on both sides > >>> to steer the current through the L6 ground layer? L5 and L6 are already > >>> coupled through the inter-plane capacitance (they're about 4mils apart). > >>> Which will provide a lower inductance path? > >>> > >>> Mike > >>> ------------------------------------------------------------------ > >>> 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 > >> > >> > >> > >> > >> > > > > > > > > ------------------------------------------------------------------ > > 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 > > _________________________________________________________________ See how Windows connects the people, information, and fun that are part of your life. http://clk.atdmt.com/MRT/go/msnnkwxp1020093175mrt/direct/01/ ------------------------------------------------------------------ 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