VLSI CMOS - Layout to Schematic help!

Discussion in 'Homework Help' started by Geza, May 18, 2009.

  1. Geza

    Thread Starter New Member

    May 18, 2009
    7
    0
    Hey guys,

    I've got my exam for VLSI coming up next week and need some help converting these layouts to schematics. Any ideas how it can be done or where I should look?

    Many thanks
     
  2. tuborggg

    Active Member

    Jan 3, 2009
    37
    0
    Hi, you need a "map" to translate it. i.e. look at the attached file
     
    • mao.JPG
      mao.JPG
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  3. Geza

    Thread Starter New Member

    May 18, 2009
    7
    0
    thanks for your quick response :) I haven't been given a map for them, is it possible to guess which pattern is the n-type substrate which is metal 1 ... etc etc from the way it is drawn?

    Cheers
     
  4. Greg_R

    Member

    May 5, 2009
    11
    0
    Yes, you can guess based on how the structures are drawn. The "legs" crossing the substrate are going to be either poly or M1. A poly between two metal legs = a transistor. Typically, for basic diagrams PMOS devices are drawn above NMOS devices (you'll see the two rows of diffusion in each problem). In the circuits without wire labels (VCC/VSS, cat, dog, etc.), start assigning arbitrary labels to keep things straight as you create the schematic. The thick horizontal wires in #2&3 are VCC (top) and VSS (bottom). Be careful though, I'm not sure if your prof wants you to guess at those labels or not.

    Note: the first diagram is evidently all NMOS devices...
     
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