Miscellaneous topics in Pre-Placement
Insertion of Decap Cells(Not everyone follows this)
As mentioned, decap cells are leaky and need to be used effectively, insertion of these cells is not mandatorily followed by all designers. It depends on the top-level team to decide to use them in layout or not.
Here fixed objects are considered as Magnets in Magnet placement. ICC Tool moves the connected Standard Cells close to them. This is done to improve congestion for complex floorplan or to improve timing for design. For better results perform Magnet Placement before placement of Standard Cells.
To specify fanout limit:
Magnet Placement allows cells to overlap. To prevent overlapping of cells use,
magent_placement_disable_overlap <variable> - true
Here Magnet Objects are Fixed Macro Cells, Pins of fixed Macro Cells, I/O pins.