Thanks for the quick reply's. Paul - I read in Bogatain's book that this method is not effective -It was mentioned under what happens when you run over a gap in the return plane but as I understand the physics is essentilay the same. To the best of my understanding the current will "find it's way back" in a radiative manner so that as long as the capacitance between the relevent planes is suffiecnt it should be ok above a certain rise time - I just don't know the numbers. Is this method effective from your experince? what's the range of Rt for which it works. Rick - Your absoulty right. I've been a bit vauge. The setup I'm talking > about is something like this: > Power 1(Real Ref.) Signal 1 Power 2 Signal 2 Power 3 Signal 3 Power 4(GND) And the relevent Signal layer is "Signal 2". The distance between different layers is 5 mil on each side. Mark > On Mon, Nov 7, 2011 at 11:24 PM, Rick Collins <gnuarm.2006@xxxxxxxxx> wrote: > I recall from a course I took that if the plane of the stripline is > tightly coupled to the reference plane, you should not have a > problem. But "tightly coupled" may not be what you have. I think > the context of what I learned was when there was a separation in a > power plane or even a signal passing across a gap between two > separate power planes, but in both cases the power planes were > opposite a ground plane and so were "tightly coupled" acting just > like the ground plane. > > Where is your driver's "reference plane" that it does not interact > with the signal? Can you give us a better picture of what you are > designing rather than talking in the abstract? > > > At 04:15 PM 11/7/2011, Mark Grobman wrote: > >Hello experts, > >I require some help on the subject of reference planes. I'm designing a > >board and despite my best efforts i'm stuck with a situation where I'm > >forced to conduct a signal using a stripline neither of whose planes are > >the reference planes of the signal's driver (not the driver's ground or > >VCC). > > > >Now I know from various App. notes and books that this sort of situation > >should be avoided and that I have been a bad engineer indeed. > > > >Still, assuming the situation cannot be avoided I was hoping to get > >some quantitative approximation to how bad of an idea this is.Sadly > >speaking I don't have access to a 3d simulator which can give me exact > >results so I'm going for best effort design methods. I would love to get > >your input on the following issues: > > > >1. Does the interference caused by not using the correct ref. planes carry > >throughout the transmission line or does it occur only at the edges where > >the current "jumps" back to the correct ref. planes? > >2. Is there a merit figure of RiseTime/planes capacitance/???? for which > >the situation isn't problematic? > >3. Will using diff. lines improve the situation? > >4. Suggested reading on the matter. > >5. Highly insightful remarks which will blow my mind. > > > >Cheers, > >Mark > > > > > >------------------------------------------------------------------ > >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 > > > >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 > > 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 Old (prior to June 6, 2001) list archives are viewable at: http://www.qsl.net/wb6tpu