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Designing a PCB for AD7367

Question asked by oscargomezf on Oct 10, 2017
Latest reply on Nov 13, 2017 by oscargomezf

I'm working on a design with the ADC: AD7367 and I have some questions about how to route the PCB, more concretely, how I have to join AGND and DGND. I was reading the reference design, but I have 6 layers instead of 4 layers.

 

My stack up has 6 layers: L1 - SIGNALS, L2 - GNDs, L3 - MIX (SIGNALs + GNDs), L4 - MIX (SIGNALs + GNDs), L5 - GNDs and L6 - SIGNALS.

 

1º.- I have in the layers L2 and L4 the planes AGND and DGND and they are separated 0.2 mm between them. Do you think is good enough?


2º.- I don't know how to join these two GND planes (AGND and DGND), because as you can see in the reference design the join is placed in the L1 with a component that is a simple track.

 

 

But in my particular design, I cannot do that because my DGND and AGND planes are in the layers L2 and L5. So If I create a simple component and I place it in the L1, I would have to place vias below the ADC [JP1 and JP2], however, I would like to avoid placing vias below an ADCs. Could I place vias of AGND and DGND below the ADC?.

 

 

  1. So, What way do you think is the best way for joining AGND and DGND?
  2. Could I place the join between the two ADCs U7 and U10, where there are DGND and AGND tags in green colour with vias.

 

Or Could I place vias of AGND and DGND below the ADC?.

 

Best regards.

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