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 non-clock tree cells on clock tree paths 

Last post Mon, Jun 16 2014 8:42 AM by chris06. 2 replies.
Started by chris06 13 Jun 2014 07:44 AM. Topic has 2 replies and 1056 views
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  • Fri, Jun 13 2014 7:44 AM

    • chris06
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    non-clock tree cells on clock tree paths Reply

    Hello,

     

    I have a question regarding the use of non-clock tree cells on clock tree paths.

    The netlist post-synthesis that I have, contains standard muxes and gating-elements on clock paths.

    During the P&R clock-tree-synthesis step, clock tree buffers are inserted but the standard muxes and gating elements are not swapped to their "clock cell" version. 

    I have 2 questions:

    1/ Is there a way to force "RTL compiler"  tool to use only clock cells on clock tree paths when synthesizing the netlist?

    2/ Is there a way to force "Encounter" tool to swap the non-clock-cells on clock paths to their "clock cell" version during clock tree synthesis step?  I mean is there a way to fully resynthesize the clock paths with clock tree cells?

     

    Thanks in advance for your help.

    Best Regards

    Chris 

     

     

    • Post Points: 20
  • Fri, Jun 13 2014 10:43 AM

    • fitz
    • Top 150 Contributor
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    • Kanata, Ontario
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    Re: non-clock tree cells on clock tree paths Reply

     Automatically ? Not that I am aware of...........
    1) RTL compiler - You manually instantiate specific clock tree cells rather than infer a mux.
    2) ENCOUNTER - You manually ecoChangeCell to the specific clock tree cell.

    Shawn

    • Post Points: 20
  • Mon, Jun 16 2014 8:42 AM

    • chris06
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    • Joined on Wed, Jun 11 2014
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    Re: non-clock tree cells on clock tree paths Reply

    Thanks Shawn for your feedback.

    Actually I use the methodology you described in 2/. I list all the cells of the different clock-trees and then swap them automatically to their "clock-cell" version. The problem I'm facing is that lot of the cells used in these clock-trees don't have an equivalent "clock-cell". For example a MUX4:1 doesn't have a CLKMUX4:1 equivalent but only CLKMUX2:1. Which means that I have to do much tricky things than simply using ecoChangeCell. Anyway, if there is no easier way I'll have to do it manually.

     

    Thanks again and best regards,

    Chris  

    • Post Points: 5
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Started by chris06 at 13 Jun 2014 07:44 AM. Topic has 2 replies.