[SI-LIST] Re: Question about split gnd planes
- From: "Lee Ritchey" <leeritchey@xxxxxxxxxxxxx>
- To: "Andrew W. Riley III" <drew3rdof3@xxxxxxxxxxxx>, si-list@xxxxxxxxxxxxx
- Date: Fri, 26 May 2006 13:49:24 -0700
Here is the location of the article on AGND vs. DGND.
> http://www.analog.com/analog_root/static/pdf/raq/RAQ_groundingADCs.pdf
Simple fix to the problem is to name both pins ground when you build the
parts, since they don't need different names on the PCB.
> [Original Message]
> From: Andrew W. Riley III <drew3rdof3@xxxxxxxxxxxx>
> To: <si-list@xxxxxxxxxxxxx>
> Date: 5/26/2006 12:38:28 PM
> Subject: [SI-LIST] Re: Question about split gnd planes
>
> Just a note,
> >> As per I know no tool will allow you
> >> to connect the AGND and DGND directly
>
> Allegro and the Altium package that I am now forced to deal with have
this
> capability. And I can't imagine that no others have the same capability.
>
> Cheers!
> Drew
>
>
> ----- Original Message -----
> From: Ayan Bhattacharyya
> To: weirsi@xxxxxxxxxx ; Manickavelu M. ; istvan.novak@xxxxxxxxxxx ; Ed
Troy ;
> si-list@xxxxxxxxxxxxx
> Sent: Friday, May 26, 2006 4:32 AM
> Subject: [SI-LIST] Re: Question about split gnd planes
>
>
> Hi,
> As per I know no tool will allow you to connect the AGND and DGND
> directly....u can connect them through CAPs also...
> Else in same ground plane u can maintain less noise interference by making
> bottle-necks in the layout for the different noise sources.
> "Istvan Novak"'s approach is a good one...ground guard signals also help a
> lot ...specially for clock signals...around crystals.
> Regards
> Ayan Bhattacharyya.
>
>
> -----Original Message-----
> From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx]
On
> Behalf Of steve weir
> Sent: Friday, May 26, 2006 4:47 PM
> To: Manickavelu M.; istvan.novak@xxxxxxxxxxx; Ed Troy;
si-list@xxxxxxxxxxxxx
> Subject: [SI-LIST] Re: Question about split gnd planes
>
> Manix, no. There are many misconceptions out there about the myth of
> ground and its relation to noise isolation. Those myths get
> propagated into misguided applications of moats and such. Think in
> fields and the misconceptions go away.
>
> Steve.
> At 09:50 PM 5/25/2006, Manickavelu M. wrote:
> >Istan,
> >Is it not that the analog and digital grounds planes can not be connected
> >together anywhere but only under the chip that sources the analog
signals?
> >Also that while coupling these two planes we should not use direct Cu
plane
> >connection but couple them via inductors?
> >
> >Manix,
> >MindTree.
> >
> >-----Original Message-----
> >From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx]
On
> >Behalf Of istvan.novak@xxxxxxxxxxx
> >Sent: Friday, May 26, 2006 6:26 AM
> >To: Ed Troy; si-list@xxxxxxxxxxxxx
> >Subject: [SI-LIST] Re: Question about split gnd planes
> >
> >Ed,
> >
> >Splitting more than one ground plane in the stackup requires a lot of
> >consideration, and mostly it is not necessary. Isolating a sensitive
> circuit
> >(e.g., analog input, low-jitter oscillator) may be a good idea, but
instead
> >of cutting a large solid ground plane, you may want to try first to put
the
> >circuit to be isolated on a grounded patch on a 'non-ground' layer. You
can
> >make ground surface patches under and around your circuit to be
isolated, or
> >you can put the patch on a signal layer.
> >
> >Regards,
> >
> >Istvan Novak
> >SUN Microsystems
> >
> >
> >From: Ed Troy <etroy@xxxxxxxxxxxxxxx>
> >Date: Thu May 25 15:38:33 CDT 2006
> >To: si-list@xxxxxxxxxxxxx
> >Subject: [SI-LIST] Question about split gnd planes
> >
> >If you have a circuit board that requires a split gnd plane over a
> >small section of the board, and you have several ground planes,
> >should only one have the split (the one nearest the side containing
> >the components that require analog ground) while the rest of the
> >ground planes are continuous, or should the split section be on all
> >ground layers? I would think that you should only have it on one
> >layer. Also, if it should only be on one layer, I would imagine it
> >would be best to connect it to the digital ground with one, and only
> >one, via. Is that generally correct? What are some good references
> >for layer stackups, etc? I know I saw one, once, but can't remember
where.
> >
> >Ed
> >
> >
>
>
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