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I am working as an intern at a start up.
We have got a project for Data Acquisition system in which we are using three RF sampling ADCs.

ADC is ADC12DJ3200 from TI which has 6.4GSPS sampling rate in single channel mode and 3.2GSPS in dual channel mode.

We are planning to use two separate ground plane, one for power (PGND) and other for all other (AGND) components like PLLs for clocking , ADCs etc.
These two ground planes will be connected using zero ohm resistor (I think this is called star grounding).

Now we are planning to use pi filter using ferrite beads and capacitors for power supply filtering for ADCs.

Our concern is C4, C2 and C3 should be connected to which ground (PGND or AGND)?

Also, is the idea of using two different ground planes helpful or not, because I have read somewhere that star grounding can create more problems if note done properly?

Any suggestions on this will be very helpful.

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schematic

simulate this circuit – Schematic created using CircuitLab

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  • \$\begingroup\$ Hi , it will be really helpful for us if someone can provide some useful suggestions. I am sure someone here definitely have used more than one ADC on single board and also star grounding \$\endgroup\$
    – Lalit
    May 13, 2019 at 14:44
  • \$\begingroup\$ I guess you should not reference your filtered power supply to PGND. I guess it's your best interest to connect it to AGND. \$\endgroup\$ May 14, 2019 at 1:23

1 Answer 1

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You might even do this

schematic

simulate this circuit – Schematic created using CircuitLab

How to keep your sampling clock to be clean?

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