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High speed ADC layout considerations

Question asked by cocopa on Aug 20, 2015
Latest reply on Aug 27, 2015 by J.Harris

Hello, I'm designing a board with 5 high speed ADCs (AD6643) driven by ADA4930-2 and i'm having some concerns regarding pcb layout and especially ground connections.

I want to isolate as much as possible one ADC chain from the other so I partitioned the ground layer trying to avoid returning currents from different ADCs interfering with each other (depicted in the attached image). There is only one point where analog and digital section are connected (near the power supply connector). Is this correct practice or should I remove the gap beneath every ADC to connect analog and digital sections at these points? (the exposed pad of the ADC belongs to analog section).

Also, I know that differential lines driving the ADC should be symmetric but since I have to use vias and a different layer to "invert" the lines (marked wih a red circle in the image), should I do that near the driver or the receiver?

Any other comments and reviews regarding the design are more than welcome.

Thank you.

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