shield ic chip at analog ground or digital ground?

[KevinLee]

Hello,


I am going to shield a few ic in my Quad 99 CDP with conductive copper and conductive aluminum tape.

If an IC has both an analog ground and a digital ground, which one should i connect the shield to?

One chip for example is a Cirrus CS4396.

Thanks

Kevin

 

[Mooly]

It probably won't make much difference in practice. (Both adding foil and where connected.)

Another slant is that the foils will (could ) pick up noise and inject it into the grounds. It works both ways although the effect would be microscopic I'm sure..

Perhaps connect the foils back to some main PSU ground (or the case) via isolating resistors of say 10 ohm...

 

[marce]

Dont bother untill you have read Henry Ott, Electromagnetic compatability engineering, then you will realise that it aint gonna do much.Shielding is an art itself, and if you have any holes or slots its a waste of time. If you look at the cans on PCB's for shielding, they have a contigous soldered join at the bottom where the ground is exposed to create a 360 degree join, you will not achieve this with foil or tape and as Mooly said may cause more noise by creating unintentional dipoles. Adding tails to some remote location is the worse thing you can do with a shield, they have to be connected at source and all the way around the shield. As the digital ground (if seperate ) will tend to be more imune to noise than analogue use the digital ground if you must play.