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Correct layout of ADA4937-2

Question asked by expjtt on Feb 3, 2018
Latest reply on Feb 5, 2018 by JinoL

Hello,

The ADA4937-2 datasheet states that the ground and power planes should be cleared near the summing nodes and gives an example for the ADA4938-1:

 

This is a bit confusing to me because it only looks like the polygon pour on the top layer is removed. I have an 8 layer board with multiple ground- and power planes. Do I understand correctly that I should remove all the power/ground planes in that region?

 

Second, the ADA4938-2 is a bit more difficult: I need thick lines for the supply to connect them to the decap and in my case, I also have a feedback cap. So it gets more crowded and I cannot cut out so generously. I have created the following layout (for simplicity I've hidden overlay):

 

The dark black area is what I have cut out on all of my 8 layers.

Is this cutout enough or should I make it larger? Or smaller?

Is this an acceptable layout? Including the decap?

 

Thanks!

Eric

 

PS: This is my first "high performance" layout.

PPS: The unrouted components are pulldown resistors for "ENABLE" and a resistive divider for the output common mode.

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