Guidelines to place Marcos

This blog describes the guidelines to place macros:

  • Place Marcos around the periphery of the chip. The main advantage is that placing macros around the core periphery is that it’s easier to supply power to them and also the chance of IR drop will be reduced.
    And if we put macros inside the center of the core it will invite serious outcomes during routing, it will create a lot of detour routing.
  • The Marcos will place based on the fly lines, and make sure you place a block that connects closer.
  • Keep the sufficient distance between two macros.

Distance between two macros = (number of pins*pitch)/number of layers either horizontal or vertical

  • Avoid crisscross placement of macro, in order to save routing resources, congestion and also avoid other issues related to timing, placement of standard cell etc
  • Try to avoid notches while placing macros, if notches are present then use hard blockages in that area.
  • Apply halos around the four sides of macros so that no standard cell will not sit near the macros pins. This technique avoids congestion.
  • To minimize the distance between pins, orient the macros.
  • Same hierarchy Marcos is placed together.
  • At least one pair of power straps (power and ground) should be present between two macros.
  • Try to put necessary blockages around the macros.
  • To avoid area loss, place macros in a simple rectangular shape

Fig: Placed macros inside the core

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