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 th...
Clock skew Arrival time of the clock Transition or Difference in clock arrival time at two spatially distinct points (TCLK1 and TCLK2) positive skew if the capture clocks comes late than launch clock then its called +skew +skew can lead to hold violations Negative skew if the capture clock comes early than launch clock it is called -skew -skew can lead to setup violations Useful skew it is a concept of delaying the capturing flop clock path this approach will helps in meeting setup requirements. setup requirement with in the launch and capture timing path. But the hold requirement has to be met for the design. Useful skew techniques can be used to fix both setup and hold violations. One disadvantage of this technique is that if the design has multiple modes of operation, then useful skew can potentially cause a problem in another mode.
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