# Connecting AGND and DGND

**URL:** <https://community.sparkfun.com/t/connecting-agnd-and-dgnd/12696>\
**Category:** PCB Design\
**Created:** [September 25, 2009, 7:16pm UTC](https://community.sparkfun.com/t/connecting-agnd-and-dgnd/12696 "2009-09-25T19:16:42Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![abrand](https://avatars.discourse-cdn.com/v4/letter/a/51bf81/32.png) [@abrand](https://community.sparkfun.com/u/abrand)\
**Post date:** [September 25, 2009, 7:16pm UTC](https://community.sparkfun.com/t/connecting-agnd-and-dgnd/12696/1 "2009-09-25T19:16:42Z")

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I had a question about connecting the AGND and DGND on a 2 layer board. I see the sparkfun library has a component for this, however the pads are not connected (as i would assume this would correspond EAGLE to believe they are the same net). Not sure if they are connected on a layer I don’t have active or if need to manually route them together.

Thanks,

Alex

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**Author:** ![leon\_heller](https://yyz1.discourse-cdn.com/sparkfun/user_avatar/community.sparkfun.com/leon_heller/32/7602_2.png) [@leon\_heller](https://community.sparkfun.com/u/leon_heller)\
**Post date:** [September 25, 2009, 7:33pm UTC](https://community.sparkfun.com/t/connecting-agnd-and-dgnd/12696/2 "2009-09-25T19:33:56Z")

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Connect them both to ground. Even if you need separate analogue and digital grounds for noise reduction, they need to be connected together at some point.

Leon

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**Author:** ![waltr](https://avatars.discourse-cdn.com/v4/letter/w/898d66/32.png) [@waltr](https://community.sparkfun.com/u/waltr)\
**Post date:** [September 25, 2009, 7:45pm UTC](https://community.sparkfun.com/t/connecting-agnd-and-dgnd/12696/3 "2009-09-25T19:45:59Z")

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I will use two grounds on a board and keep them as different net names. This way you control where current returns paths are and where they are connected together. Leave them un-connected until all DRCs pass and the layout is completed. Then as the last step tie them together with a copper trace.

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**Author:** ![MichaelN](https://avatars.discourse-cdn.com/v4/letter/m/b19c9b/32.png) [@MichaelN](https://community.sparkfun.com/u/MichaelN)\
**Post date:** [September 26, 2009, 12:11am UTC](https://community.sparkfun.com/t/connecting-agnd-and-dgnd/12696/4 "2009-09-26T00:11:04Z")

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split ground planes are generally frowned on these days (for EMC reasons as much as anything). Some datasheets still have recommendations that are not best-practice.

When you do use split planes, you have to take a lot of care about return paths (and not creating large current loops due to the split). It is normally better to properly segregate analog / digital sections rather than put split planes.

Have a look at this; you have to register (free) but Keith’s advice is well worth it:

[http://www.compliance-club.com/KeithArm … artid=4152](http://www.compliance-club.com/KeithArmstrong_Article.aspx?artid=4152)