Hi, I’'m connecting a A/D converter to a microcontroller, and am creating the board in Eagle. I have the A/D as well as the input signal grounds connected to an analog ground plane that is a little copper island within the main fill of the regular ground plane. Does anyone know how I can connect the analog and digital ground planes?
Thanks! Rand
There are a couple of ways you can do it.
The first is to simply rename one of your ground planes so they are both the same. This should allow you to physically connect them on your board.
The second is to connect the two ground planes in your schematic. When you switch to your board view, you should see an airwire connecting the two planes. You can then route it however you want.
If all else fails you can trick the software by drawing lines in an unused layer that connect the two planes. When you go to export your gerber files in the CAM processor, select that layer as part of your top or bottom copper depending on where your ground planes are.
-Bill
So essentially, there’s no elegant way to do it? The problem with naming the signals the same thing, or connecting them in the schematic (which seems to rename them to the same thing) is that they then become just one signal plane, and the ratsnest command will fill in all of the plane seperation I’ve made.
this problem exists because you want to use the autorouter, right? With manual routing, you can control trace positioning. I would recommend you not use the autorouter for the analog section since you have little control over the layout.
Note that you can use the polygon tool to draw an arbitrarily shaped ground plane. My guess is you are creating just a rectangle.
You could create a device, let’s call it link, that has 2 smd pads and copper between them. then you use AGND and GND for your different grounds and connect one side of link to AGND, the other to GND.