DCoperatingparameters

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Show DC operating parameters

This guide will show you how to show DC operating parameters like gm, R_{out} V_{th} etc for all your transistors in a Cadence schematic.

If you just want to save all parameters to a file have a look at this guide instead: Transistor operating point printer

Steps

  1. Create your circuit in a schematic
  2. Set up a DC simulation, check the "save operating point"-box in the creating of the test
  3. Go back to your schematic window and at the top-men click:
  4. View - Annotations - DC Operating Points. This will give a default selection of parameters
    The annotation menu
  5. To chose which to view in your schematic go back to View - Annotations and at the bottom click "Setup.."
  6. Make sure the library-drop-down is showing "tsmc13rf" (or your transistor library), choose pmos in "Cell" and leave instance to "*" if you want to change it for all transistors in your sheet.
  7. Here you can see the list that is showing by default and three "free" cells at the rows Parameter:cdsPara(6), (7) and (8)
  8. Double click in the column "Expression" for those rows and select the parameter you want to show (i.e region, rout, gm, gds)
    The annotation setup window
    • You might want to disable annotation of the first four rows here to hide some annotation noise
  9. Click apply and repeat the same steps for the nmos cell
    PMOS with parameters showing
  10. Save this annotation set-up by clicking File - Save. Chose the default location to make it easy for yourself. (If you don't save you have to do this set-up every time you close Virtuoso)
    • The next time you load your design just click View - Annotations - Setup.. and then File - Load - OK


Note

  • Region 0 is cutoff
  • Region 1 is linear
  • Region 2 is saturation
  • Region 3 is subthreshold
  • Region 4 is breakdown
  • Type 0 is nMOS
  • Type 1 is pMOS