[SI-LIST] Re: Separate GND for Analog & Digital
- From: "Chris McGrath" <chris.mcgrath@xxxxxxxx>
- To: <si-list@xxxxxxxxxxxxx>
- Date: Fri, 20 Feb 2004 07:55:53 -0800
I agree that the main issue is to isolate the return paths by connecting
the grounds together at a single point and this is a pretty easy thing
to do and you don't need additional ground planes to do it.
That having been said, Zhangkun mentioned some CAD tools that can do
simulations to test this. Forgive my ignorance, but would this be in
the form of setting up digital aggressor nets to determine if they have
any affect on the analog areas in this isolated ground area?
Thanks,
Chris
> -----Original Message-----
> From: Zhangkun [mailto:zhang_kun@xxxxxxxxxx]=20
> Sent: Thursday, February 19, 2004 8:13 PM
> To: maheshwari@xxxxxxxxxx; si-list@xxxxxxxxxxxxx
> Subject: [SI-LIST] Re: Separate GND for Analog & Digital
>=20
>=20
> Dear Maheshwari
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> We have come cross the simular problem. The critial point is=20
> to prevent return path of digital signal disturbing the analog signal.
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> In one of our PCB, there is too much digital noise in analog=20
> signal. We have to repair it. How to seperate the ground=20
> seemed to be the most important problem. One is to seperate=20
> the ground and to connect the digital ground and analog=20
> ground at one point. The other is not to seperate the ground.=20
> In order to make sure that the product is OK, we made two=20
> boards, seperated and not seperated. In the test, both boards are OK.
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> It has nothing to do with seperating ground or not. Being=20
> care of the digital return path is the most important. Some=20
> CAD tools could do such simulation.
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> I hope this will help.
>=20
> Best Regards
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> Zhangkun
> 2004.2.20
>=20
> ----- Original Message -----=20
> From: "Maheshwari.P" <maheshwari@xxxxxxxxxx>
> To: <si-list@xxxxxxxxxxxxx>
> Sent: Thursday, February 19, 2004 7:41 PM
> Subject: [SI-LIST] Separate GND for Analog & Digital
>=20
>=20
> > Hi All,
> >=20
> > I am designing boards which contain Audio and Video codecs.=20
> I need to=20
> > pass analog signal to the corresponding decoders without much noise.
> >=20
> > Is it better to have separate analog and digital GND?
> > or
> >=20
> > Is it better to have a solid GND and have separate analog=20
> and digital=20
> > sections?
> >=20
> > Which of the either way will give better results in terms=20
> of audio and=20
> > video quality?
> >=20
> > Thanks in advance,
> > Maheshwari
> >=20
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