[SI-LIST] Re: XAUI

Steve,

Do you mean by PP preperg?  If so, that would infer what is often called
broadside coupling or one over the top of the other.  If that is what you
mean by this, it's about the worst way there is to route a diff pair and I
would never want to do that.  It is really a tough one to get right.

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: steve weir <weirsi@xxxxxxxxxx>
> To: <leeritchey@xxxxxxxxxxxxx>; Ravindra Johari
<Ravindra.Johari@xxxxxxxxxxxxxxxxxx>; <si-list@xxxxxxxxxxxxx>
> Date: 12/22/2005 6:38:13 PM
> Subject: Re: [SI-LIST] Re: XAUI
>
> Lee, I agree that loosely coupled usually brings fewer issues to deal
with 
> than tightly coupled, making it a safer default recommendation.  For 
> loosely coupled, I would avoid broadside coupling including tandems, 
> particularly across PP.  If B/S coupled across PP, the registration, and 
> therefore coupling can vary quite a bit, especially for narrow traces. 
If 
> the PP is thin, it just makes it worse.
>
> Steve.
> At 02:17 PM 12/22/2005 -0800, Lee Ritchey wrote:
> >Actually, neither.  Coupling doesn't have any benefit.  If you can spread
> >the traces out so there is no coupling, you've got the best geometry. 
Real
> >world, you can't do this and route a PCB, so route side by side with as
> >much separation as your topology will allow.  Then adjust trace widths to
> >give you 100 ohm diff impedance.
> >
> >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: Ravindra Johari <Ravindra.Johari@xxxxxxxxxxxxxxxxxx>
> > > To: <si-list@xxxxxxxxxxxxx>
> > > Date: 12/22/2005 11:19:44 AM
> > > Subject: [SI-LIST] XAUI
> > >
> > >
> > > Hello Gurus!!
> > >
> > >
> > >
> > > Which is a better coupling for running a differential pair at XAUI
Speeds
> > > i.e at 3 Gbps..
> > >
> > >
> > >
> > > Is it Edge coupled stripline or Broadside coupled stripline..
> > >
> > > What kind of constraints can I face with these?
> > >
> > >
> > >
> > > Thanks!
> > >
> > > Ravi
> > >
> > >
> > >
> > >
> > >
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