Back Annotation simulations

Discussion in 'VHDL' started by rajan, Aug 7, 2004.

  1. rajan

    rajan Guest

    Hi colleagues,

    I have got a SDF file from another colleague. I need to do back-annotated
    simulations on this design. Now I would like to know what tools and the
    procedure should be followed for doing the back-annotation simulations. This
    is the first time for me to do back-annotated simulations.

    Thanks in advance.
    rajan, Aug 7, 2004
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  2. rajan

    Niv Guest

    You'll need the gate level .vhd file that goes with the .sdf file.
    (I think).
    Niv, Aug 8, 2004
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  3. rajan

    Lee Guest


    I think you can do time analysis and power analysis in PrimeTime and
    Power compiler of Synopsys respectively. Those tools can work on gate
    level netlist, usually for architecture design.

    In PrimeTime and power compiler, if you don't use SDF file, you can
    define a wireload model to estimate the wire parasistics and
    resistance. Anyway, the model is not accurate, since it doesn't
    consider placement&route. So you need back-annotation.

    I think SDF file only talk about the wires (P&R) but gates. Gates
    information can be extracted from Synopsys library.

    If you already extracted transistor level netlist from layout. You can
    run Hspice, Spetre or NanoSim (much faster) for the simulation. In
    this case, the back-annotation is not neccessary.

    If I am not right, correct me please.
    Lee, Aug 8, 2004
  4. rajan

    rajan Guest


    Thanks a lot. In case of doing back-annotation, which tools can be used. Is
    this possible with NCsim? Also, is the procedure of doing the
    back-annotation same as normal functional simulations with NCsim?

    rajan, Aug 8, 2004
  5. Hi,

    usually you instantiate the netlist in a testbench, compile the netlist and
    the testbench and start the simulator.
    You also need the compiled library for the gate primitives.

    The sdf file can be overlayed for timing simulations. Check the simulator
    docs on how to do that.
    For modelsim the invocation command for the simulator may look like this

    vsim -sdftyp /tb_netlist/dut=/home/sim/ab/xc_nl/evalTop_timesim.sdf -t ps

    -sdftyp determines which of the timings in the sdf triplet file will be used
    (min, typ or max). You may get different sdf files for different operating
    /tb_netlist/dut is the hierarchy on which the sdf is overlayed
    /home//sim/ab/xc_nl/evalTop_timesim.sdf is the the path and the filename of
    the sdf file.
    work.cfg_tb_netlist is the testbench configuration


    Ansgar Bambynek, Aug 10, 2004
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