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 Saving the device information 

Last post Wed, Jul 31 2013 3:27 AM by rkkIITB. 8 replies.
Started by rkkIITB 31 Jul 2013 01:32 AM. Topic has 8 replies and 810 views
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  • Wed, Jul 31 2013 1:32 AM

    • rkkIITB
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    Saving the device information Reply

    Hi,

    I am simulating a simple circuit with a MOSFET whose instance name is M0.

    In the simulator input file, I have specified "save M0:oppoint" .

    However, simulator gives warnings as below,

    "Warning from spectre during initial setup.
        WARNING (SPECTRE-8061): `M0': Does not have a terminal named `oppoint'.
        WARNING (SPECTRE-8287): Ignoring invalid item `M0:oppoint' in save
            statement.
    "

    Can you please let me know how I can see the parameters of the mosfet for the entire simulation time in a transient simulation.

    I am using the following version of spectre

    Cadence (R) Virtuoso (R) Spectre (R) Circuit Simulator
    Version 7.2.0.442.isr15 32bit

    Also, can you please help me to do the same using ADE.(not manually editing the simulator input file)

    Thanks in advance.

    • Post Points: 35
  • Wed, Jul 31 2013 1:58 AM

    • mate0409
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    Re: Saving the device information Reply

     Hi,

    have you tried to add

    save M0:all

    With Regards,

    • Post Points: 20
  • Wed, Jul 31 2013 2:03 AM

    • mate0409
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    Re: Saving the device information Reply

     By the way, you can use the OPT command inside the calculator to save operating points during a transient analysis

    (From the help manual: OPT: Returns the transient operating point for the specified instance parameter.)

    • Post Points: 5
  • Wed, Jul 31 2013 2:10 AM

    • rkkIITB
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    Re: Saving the device information Reply

    Hey mate,

    save M0:all is not working.

    The log file says:

    Warning from spectre during initial setup.
        WARNING: subcktInst:all is not supported.
        WARNING (SPECTRE-8287): Ignoring invalid item `M0:all' in save statement.

    Regards,

    KK

    • Post Points: 20
  • Wed, Jul 31 2013 2:20 AM

    • mate0409
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    Re: Saving the device information Reply

    Maybe your transistor is modeled inside a subcircuit. If it is, then you have include your subcircuit name in the expression. That is:

    save M0.subCktName:all

    If your subCircuit is named XXX, then the expression would be (saving cdb)

     M0.XXX:cdb 

     Maybe this is also the reason why you could not access the operating points via M0.oppoint

    • Post Points: 20
  • Wed, Jul 31 2013 2:36 AM

    • rkkIITB
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    Re: Saving the device information Reply

    Mate,

    I had already checked about the subckt. My transistor is not modeled inside any subckt.

    --KK

    • Post Points: 20
  • Wed, Jul 31 2013 2:51 AM

    • mate0409
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    Re: Saving the device information Reply

     If i want to save op from a transitor i include this file ( example.scs ) via Setup->Model Libraries. I'm not sure if you include the file this way, but you could give it a try.

    This is a post regarding the same topic:

     This is a very commonly asked question.

    Create a text file (called, say, saveop.scs) with the following contents:

    // include file to save op point data
    save M0:all

    where M0 is the name of the mosfet. See "spectre -h save" for more details on the save statement.

    Then, in Setup->Model Libraries, reference this file (I gave it a .scs suffix so it is interpreted in spectre syntax)

     

     Check if its supported with your version

    • Post Points: 20
  • Wed, Jul 31 2013 3:13 AM

    Re: Saving the device information Reply

    KK,

    The error message you posted makes it very clear that you DO have your model defined as a subckt. For example, if I run this:

     //

    model nch bsim4 type=n

    subckt nmos (D G S B)
    parameters w=1u l=1u
    M1 (D G S B) nch w=w l=l
    ends nmos

    M1 (d g 0 0) nmos w=2u l=0.5u
    M2 (d g 0 0) nch w=3u l=0.5u

    dc dc

    save M1:oppoint
    save M1:all
    save M2:oppoint
    save M2:all

    Then I get:

        WARNING (SPECTRE-8061): `M1': Does not have a terminal named `oppoint'.
        WARNING (SPECTRE-8287): Ignoring invalid item `M1:oppoint' in save
            statement.
        WARNING: subcktInst:all is not supported.
        WARNING (SPECTRE-8287): Ignoring invalid item `M1:all' in save statement.

     Which is what you saw. The M2 device doesn't complain because it's a direct instance.

    Note that saving operating point data via the save statement has been supported forever as far as I know - so should not be version-specific.

    Regards,

    Andrew.

    • Post Points: 20
  • Wed, Jul 31 2013 3:27 AM

    • rkkIITB
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    Re: Saving the device information Reply

    Andrew,

    Whatever you told is right.

    My transistors have a subckt by the name m1.

    Mate,

    Thanks for pointing the same earlier. I had not noticed in depth.

    Thanks,

    KK

    • Post Points: 5
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Started by rkkIITB at 31 Jul 2013 01:32 AM. Topic has 8 replies.