Re: gEDA-user: Connecting AGND with GND

[Steve Meier <smeier@xxxxxxxxxxxxxxxxxxx>]

Maybe. Noise levels generally apear to be different. The reducing of the
connection between the two planes is probably as effective. One
advantage of the inductor is that you can break the path entirerly if
you have a problem.

I tend to do this a lot with subsections of a complex board. Each
section has its own filtered power supplies (inductor and caps).  Again
have a problem with the board start depowering sections of it by
removing inductors. Or better yet power the board up one section at a time.

I would like to re-iterate. Read the data sheets paying attention to the
layout and groundiing sections. High Frequency circuits can break into
oscillation very easily. There is almost always a predictable reason and
those reasons are found in the layout and grounding sections of the data
sheets.

This would be a cool feature for a cad package. having these sections
encapsolated into the symbols and land patterns. Then as you are laying
them out to be able to get a report.

Steve Meier

Dave McGuire wrote:
> On Jun 17, 2008, at 6:49 PM, Steve Meier wrote:
>   
>> Take a look at your data sheet for the ADC often these devices will
>> require both analog and digiital ground and often they will  
>> recomend you
>> connect the two grounds close to them. Second I try to keep the  
>> digital
>> ground away from the analog sections. Third try to avoid traces
>> (requiring impedence matching) crossing over moats.
>>
>> I have been using surface mount power inductors to connect the two
>> grounds. e.g coilcraft  SLC7530
>>     
>
>    This is an interesting idea; do they serve as chokes to keep noise  
> in one ground system from crossing over into the other?
>
>            -Dave
>   
>
>
>   



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