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How to optimize level shifter and isolation instances marked dont touch in Encounter

fieldy

Hi All,

 

I am implementing a Low-power design with Power switches and Isolation cells. I have a CPF file that I commit and I can see that isolation cells and level shifters are inserted into the design correctly as I intended.

However, whenever I run optDesign, whether it be preCTS, postCTS or postRoute, Encounter seem to mark level shifters and isolation instances as don't touch instances and does not optimize them. As a result, the drive strength of the isolation instances are too small. I know that Encounter doesn't optimize clock nets but there is a ckECO option to take care of clock optimization. Is there a way to make Encounter optimize the level shifter and isolation instances and/or remove the dont touch marking on these instances?

 Below are the messages I get in the log file when I run optDesign :

*info: Marking 12 level shifter instances dont touch

*info: Marking 64 isolation instances dont touch 

 

I've tried to use set_dont_touch and set_interactive_constraint_mode options to override this but haven't succeeded so far. Has anybody gotten the same problem and does anybody know how to solve this?

 

Thanks

Saekyu 

Parents

  • setOptMode  -resizeShifterAndIsoInsts {true | false}
    Controls whether timing optimization resizes shifters and isolation instances. In default mode (false), shifters and isolations are considered "don't-touch" instances and are not changed during timing optimization.
    When this parameter is set to true, the shifters and isolation cells are resized for timing optimization by using optDesign.
    Note: When this parameter is set to true, all the shifters and isolation cells can be resized even if they are marked as dont_touch.
    Default: false

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  • setOptMode  -resizeShifterAndIsoInsts {true | false}
    Controls whether timing optimization resizes shifters and isolation instances. In default mode (false), shifters and isolations are considered "don't-touch" instances and are not changed during timing optimization.
    When this parameter is set to true, the shifters and isolation cells are resized for timing optimization by using optDesign.
    Note: When this parameter is set to true, all the shifters and isolation cells can be resized even if they are marked as dont_touch.
    Default: false

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