FPGA infrastructure#

Learning goals:

  • Be able to recognize chip structures, especially memory

  • Know what the main components of an FPGA fabric are

Locating memory on a die image#

Are you curious about how an FPGA look like inside? Siliconpron houses integrated circuit die images including FPGAs.

Exercise 181

Analyze the die image of an AMD 7-Series Artix FPGA xc7a50t.

Memory cells tend to have a very homogeneous and dense structure. Try to guess which patterns on the image could depict memory elements.

Analyzing the floorplan of an FPGA#

After you guessed which areas could house memory cells, we will test your guesses using a floorplan of xc7a50t in Vivado:

  1. Fire up Vivado and click on New project.

  2. Select as Project Type I/O Planning Project.

  3. In Import Ports (optional) window click Do not import I/O ports ....

  4. In Default Part window, search for xc7a50t and select one of them.

    The shown parts only differ in their I/O Pin Count and Available IOBs but not in any of the logic resources. This is a sign that they all have the same die.

  5. Finish the project wizard. You will see the I/O design window. On the right side you have Package and Device tabs.

    A single die can have different packages to meet different application requirements like maximum chip size, required number of data signals, temperature range etc. A die is connected to the pins of a package via a process called wire bonding. An example image is here. You see that the chip is bonded to the package using the pads on its four edges.

    Now click on the Device and maximize the window.

Zoom in and browse the components. You can see the name of these components by hovering on them.

FPGA components#

Exercise 182

Which major components do you find on the FPGA fabric and what could the purpose of each component?

Comparing floorplan and die image structures#

Exercise 183

Now try to match the features on the die image to the components on the floor plan. You should at least be able to recognize block RAMs.