We use this technique often, and it does work. Just imagine the current
paths.

Fred Pescitelli
Phoenix Designs
1285 Turner Rd.
Lilburn, GA  30047
[log in to unmask]
V-770-923-3465
F-770-923-2272

> -----Original Message-----
> From: DesignerCouncil [mailto:[log in to unmask]]On Behalf Of
> Dennis Ward
> Sent: Friday, April 28, 2000 10:26 AM
> To: [log in to unmask]
> Subject: [DC] Moats
>
>
> Good morning everyone,
>
> Plese bear with me on this one. Basically an
> engineer and I are having a p!##ing contest
> concerning moats.
>
> On the design he wants a "moat" placed on the
> ground plane around certain power pins.
>
> Now this moat is NOT an isolated plane. Basically
> it is a long "U" shaped slot in the ground plane.
> His reasoning is that it keeps noise from coupling
> onto the pins.
>
> Does anyone practice this? I understand isolating planes,
> especially analog/digital circuitry. However this slot
> in the ground plane does not make sense to me. The
> pins aren't not truly isolated from the plane.
>
> Now I've looked in the "High-Speed Digital Design" book
> and didn't find info on this subject. Plenty on crosstalk
> over slots, how to moat (true moats) and things of that
> nature. I've looked on the email archives and checked out
> a few web sites. Still no definite answer. Someone please
> enlighten me.
>
> Thanks
> Dennis