Sunday 30 August 2015

Some Basic Rules For Placing Macros

     Macro placement

Once you have the size & shape of the floorplan ready and initialized the floorplan, thereby creating standard cell rows, you are now ready to hand place your macros. Do not use any auto placement, I have not seen anything that works. Flylines in your tool will show you the connection between the macros and standard cells or IOs.

  1. Use flylines and make sure you place blocks that connects to each other closer
  2. For a full-chip, if hard macros connect to IOs, place them near the respective IOs
  3. Consider the power straps while placing macros. You can club macros/memories
  4. Creating Power Rings and Straps
  5. Avoided the placement of macros in front of ports.
  6.  Arranged the macros to get contiguous core area.
  7. Macro spacing given by  space={[(no. of pins) * pitch] + space} / (no of metal layers in horizontal or vertical direction)


  1. "Macro spacing given by space={[(no. of pins) * pitch] + space} / (no of metal layers in horizontal or vertical direction)"

    is this pitch means metal to metal spacing?
    but it might vary from metal to metal, so we can't take it as a constant for multiplication.
    correct me if i'm wrong.

    1. This comment has been removed by the author.

    2. i thing in general we take the pitch of highest metal layer. that pitch value is provided in technology file.

  2. yes correct,the metal spaces varies metal to metal. but this formula not a thumb rule you can have extra spaces between macros. The pitch used here is, at-least we need to have spacing value of the metal layer used for Macro Pins.

  3. (no of metal layers in horizontal or vertical direction)"
    y we r not taking both

  4. Which space value we have to give

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