Equivalent width of a transistor (Cadence extraction)

Discussion in 'Cadence' started by Xiaofeng Wang, Oct 10, 2003.

  1. Hi, all:

    I have a question on the effective width of a transistor layout.
    the layout is at http://wangxf.nease.net/temp/transistor.bmp

    (The drawing is not to scale, the shape is actually a square.)

    I drawed the layout in cadence and did the extraction. Cadence gave an
    effective transistor. The effective width is around 47um, while the effective
    length is around 0.5um.

    I know the effective width is due to the corner effect.
    But I have some confusion about the effective length. Why it is half of the
    physical length. I tried different length, and it seemed the effective length
    is always half of the physical length. Can anyone tell me why? Is Cadence
    extraction accurate?


    Best Regards,

    Xiaofeng Wang, Oct 10, 2003
  2. Xiaofeng,

    The answer is entirely dependent on the technology and the rules being used
    to do the extraction - any computation of effective widths and lengths would be
    done there, presumably. It's not something that the extraction tool (whichever
    you're using) would do on a general basis.


    Andrew Beckett, Oct 13, 2003
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