Looking through the Digilent Arty A7 evaluation board's schematic and noticed that there are two capacitors banks connected to the core supply voltage of the FPGA (VCCINT pins). I was curious about the reasoning behind this design choice.

Why would they do this? From my understanding it seems as though the two banks would appear as one bank to the FPGA, am I incorrect with this assumption?

enter image description here

The capacitors in the red box are DNI (Do Not Install) for a certain chip, there are two tiers of this evaluation board based on the FPGA needed by the user. The DNI flag does not apply for the part shown in the screenshot.

More information about the evaluation board can be found on Digilent's website.

  • \$\begingroup\$ It's not clear what you are asking. The FPGA doesn't "see" these caps. They are for power supply filtering. \$\endgroup\$
    – jwh20
    Jan 7, 2021 at 19:56
  • 3
    \$\begingroup\$ What does the actual PCB layout look like? I think you'll find that those caps are not placed in banks on the PCB, but are spread around the FPGA such that each of the VCCINT pins has 1 or 2 caps right next to the pin - that's how supply bypass caps should be placed. \$\endgroup\$
    – brhans
    Jan 7, 2021 at 20:03
  • \$\begingroup\$ @brhans it looks like you're correct, some of the larger capacitors are a little further off than I would have expected. Just looking at the schematic it caught my eye as strange. Thanks. \$\endgroup\$
    – dby
    Jan 7, 2021 at 21:01


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