[SI-LIST] Re: Power - Ground Swap in PCB

At first look, I can't see why there would be any difference since we don't
know what's happening on the signal layers.  If power and ground are well
decoupled (and even if they aren't), they will both act as reference planes
for the signals adjacent to them.  The killer in the stackup you've
described is moving signals from one reference plane to another without a
very closely coupled current return path.

With respect,

Brent DeWitt

> -----Original Message-----
> From: si-list-bounce@xxxxxxxxxxxxx
> [mailto:si-list-bounce@xxxxxxxxxxxxx]On Behalf Of Mehrdad Salami
> Sent: Sunday, April 25, 2004 8:03 PM
> To: si-list@xxxxxxxxxxxxx
> Subject: [SI-LIST] Power - Ground Swap in PCB
>
>
> Hello All,
>
> I have a question about layer stack in PCBs. For a simple six layer like
> (configuration 1)
>
> Top (Signal1)
> Ground
> Signal2
> Signal3
> Power
> Bottom (Signal4)
>
> What would be the effect if the Ground and Power planes are swapped
> (configuration 2)
>
> Top (Signal1)
> Power
> Signal2
> Signal3
> Ground
> Bottom (Signal4)
>
> Assuming the same distance between Power or Ground to signal layers and
> also the same track routing on the signal layers.
>
>
> Regards
>
>
>
> Sal
>
> ==========================================
> Mehrdad Salami
> Hardware Design Engineer
>
> Colour Vision Systems
> 11 - Park St - Bacchus Marsh
> Victoria - 3340 - Australia
>
>
>
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