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design logic gate different strength

sam andro

I am trying to design an inverter (1x) with different strength so it is loaded by another inverter (2x), while the width of the first inverter is (W) the second one is (4w).

the point is, I wanna make parametric sweep for w from 1.2um to 504um ( which is the min and max width of that technology respectively), but when (W) is 504um the second inverter will be (4 * 504um) which is not realistic as the maximum width is 504um only.

 so how can i decrease the factor of (4) as the width of the first inverter increasing in the parametric sweep, so when the first inverter for example reaches 250um the factor of (4) will be decreased to be (2) to make the second inverter 500um which will not pass the max width of that technology.

 

Regards

  • Hi sam

    For the 2nd inverter, please use the following expression for width:

    w<=126u ? 4*w : 500u

    If w <= 126u, spectre will set the width of inverter2 as 4*w. For w>126u, the width will be a fixed value of 500u.

    You can read more about such programmable syntax in "Parameter Specification and Modelling Features" chapter in $MMSIMHOME/doc/spectreuser/spectreuser.pdf.

    Best regards
    Quek

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