KEEPOUT MARGIN

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Keepout margin: This the one of the technique using during placement macros and standard cells in the core area. It is the region around the boundary of fixed cells in a block in which no other cells are placed. The width of the keep-out margin on each side of the fixed cell can be the same or different. Keeping the placement of cells, macros etc.. This technique can  avoids congestion and nets detouring and timings. For the best quality of results.


How we decide the margin? 
The margin is decided based on the macros or IPs .These macros and IPs will come from vendors its clearly mention in the document regarding the margin around the macros like expected values will be mentioned, by reading the document we can get the values will giving the values we may increase or decrease depend on the problem we faced in the core area. For the std cells, basically we will keep out margin to mainly for AOI ,IOA and Multibit flops etc. Why only AOI, IOA and multibit flops because these cells will have more number of pins, so we required more number of routing resources HV so it may leads to high congestion so we need to avoid the congestion will place the keep out margin.  example for memories usually (1.5 to 2 um) based on the pin densities.
 






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