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How to write sdc for pre/post CTS ?

yamakazu

I want to set different clock uncertainity values in the same sdc file for both pre and post CTS modes. Can I do that ? The following sdc didn't work. How to do that ?

if {[getAnalysisMode -clockPropagation -quiet] == "forcedIdeal"} {
    set jit_add 0.2
} else {
    set jit_add 0
}
set_clock_uncertainty [expr 0.200+${jit_add}] \
  -from [get_clocks {my_clk}] -to [get_clocks {my_clk}]

Parents
  • fitz
    You missed the point completely ... one source to rule them all. ( or as few as possible )
    Let the tools take care of the preCTS and postCTS variations for you.
    You modify your optimization stage margins within the run script not the constraints.

    In the real MMMC world there is rarely just one clock , never one mode and you are guaranteed more than one corner.
    You cannot possibly keep track of all the combinations and permutations manually ... Let the tools do the work for you!!

    My current very old school 65nm SOC eco has 5 separate clocks, two functional modes and three DFT modes across four corners.
    That’s 5 ideal mode constraint source files across 4 corners ... and do the math ... 20 postCTS variants.
    Wait till you see the 14nm corners!

    As always the K.I.S.S. principal rules supreme ... Let the tools do their job.

    Shawn
Reply
  • fitz
    You missed the point completely ... one source to rule them all. ( or as few as possible )
    Let the tools take care of the preCTS and postCTS variations for you.
    You modify your optimization stage margins within the run script not the constraints.

    In the real MMMC world there is rarely just one clock , never one mode and you are guaranteed more than one corner.
    You cannot possibly keep track of all the combinations and permutations manually ... Let the tools do the work for you!!

    My current very old school 65nm SOC eco has 5 separate clocks, two functional modes and three DFT modes across four corners.
    That’s 5 ideal mode constraint source files across 4 corners ... and do the math ... 20 postCTS variants.
    Wait till you see the 14nm corners!

    As always the K.I.S.S. principal rules supreme ... Let the tools do their job.

    Shawn
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