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    Help in understanding innovus

    Dear all,
    I am new to innovus tool. I have attached the timing report taken after placing my standard cell. I would like to understand a few things in the report. What does TNS = 0 mean? What does max_tran mean? It is giving a negative number. What does that mean?

    TIA

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    Re: Help in understanding innovus

    TNS ist the total negative slack. Its the sum off the violating slacks on all paths. TNS=0 means you are good!
    Max transition means that the clock transition is to slow on some paths (it violates the constraints you gave them). Have you built a clock tree yet?


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    Re: Help in understanding innovus

    innovus tool should have a user reference manual, you can refer there for details.
    FPGA enthusiast!



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    Re: Help in understanding innovus

    Quote Originally Posted by Alexxk View Post
    Max transition means that the clock transition is to slow on some paths (it violates the constraints you gave them).
    this is not what a max tran violation is.
    Really, I am not Sam.



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    Re: Help in understanding innovus

    Sir,
    What does max tran mean? What is the nominal value of that?



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  6. #6
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    Re: Help in understanding innovus

    max tran violation means a maximum transition time violation on any pin. it doesn't have to be on the clock tree cells, it can happen on any cell. there are two reasons why max tran violations appear:
    1) your standard cells are characterised to work in a certain range. a max tran violation might indicate that a cell is working outside its characterization range and therefore the tool had to guess its timing by extrapolating. this is not good, but won't necessarily kill the chip.
    2) the designer sets a max tran target that is more strict than the default from the std cell library. this is typically used to help with high-speed designs so all signals transition faster and are less susceptible to glitches/coupling. a violation of this kind could have an impact on closure and make the design time increase.
    Really, I am not Sam.


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