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How to SET temperature for the layout flow and SDF generation.

Navid T

 Dear friends,

For some reason, I need to set the temperature to something different than the temperature set by the PVT corner. For example, in the typical PVT corner, temp = 25, I'd like to change it to 50 and then have the Encounter to write an SDF for simulations. I also like to set the temperature to 50 and then use the typical PVT corner as the max lib and do the whole layout flow based on that.

(you might say you always need to consider worst PVT, but I'm doing some research, and thus, I need to set the temperature to what I need and then get the delays at that temperature).

Any ideas how I can do that? I appreciate your help.

Best,

Navid

  • I'm not sure if you want to scale the cell delays based on temperature -or- whether you want to scale net resistance based on temperature.  If it's the former, I don't recall ever seeing that done- I think you need to have a different .lib for each temperature.

    If it's the latter, you can scale the net resistance with:

    encounter 33> help defineRCCorner
    Usage: defineRCCorner {-late {best | typical | worst}
                          [<temp>] -early {best | typical
                          | worst} [<temp>]} | {-latespef
                          <fileName> -earlyspef <fileName>}

     (or if you're using MMMC mechanisms to establish your timing environment):

    encounter 31> help create_rc_corner
    Usage: create_rc_corner -name <rcCornerName> [-cap_table
                            <capTableFile>] [-T <rcTemperatureValue>]
                            [-default_res_factor <float>]
                            [-detailed_res_factor <float>]
                            [-res_factor <float>] [-default_cap_factor
                            <float>] [-detailed_cap_factor
                            <float>] [-xcap_factor <float>]
                            [-qx_lib_file <fileName>] [-qx_tech_file
                            <fileName>] [-qx_conf_file <fileName>]

    Hope this helps,
    Bob

  •  You can do some Hspice simulation and put different temperature in the sp file.

    The difference of cell delay will give you some hints. 

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