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power differences after post-syn using VCD

leez2006

Hi,

I want to get a quick look at the power consumption of one block.

--use RTL Compiler generate netlist(after syn) and sdf

--run gate sim with or without sdf annotated, get VCD

--use netlist and VCD in ETS, get power consumption

I found the power consumption get form VCD without sdf annotated is much greater than with sdf annotated.

This makes me confuse. I think the power with sdf annotated should be bigger. Can anyone help to explain this?

I found there is only one difference with the log (the value changes got from vcd).

without sdf annotated:

With this vcd command,  12005021 value changes and 1e-06 second
simulation time were counted for power consumption calculation.

  Filename (activity)                    :
../in/ad9651_datapath_top_gate.vcd
  Names in file that matched to design   : 234754/352833
  Annotation coverage for this file      : 54305/54305 = 100%

Activity annotation summary:
        Primary Inputs : 89/89 = 100%
          Flop outputs : 8172/8172 = 100%
  Memory/Macro outputs : 0/0 = 0%
      Tristate outputs : 0/0 = 0%
            Total Nets : 54305/54305 = 100%

with sdf annotated:

With this vcd command,  6867391 value changes and 1e-06 second
simulation time were counted for power consumption calculation.

  Filename (activity)                    :
../in/ad9651_datapath_top_gate.vcd
  Names in file that matched to design   : 234754/352833
  Annotation coverage for this file      : 54305/54305 = 100%


Activity annotation summary:
        Primary Inputs : 89/89 = 100%
          Flop outputs : 8172/8172 = 100%
  Memory/Macro outputs : 0/0 = 0%
      Tristate outputs : 0/0 = 0%
            Total Nets : 54305/54305 = 100%

Parents

  •  HI leez2006,

     not sure what you are trying to compare. Is it

     gates + activity(RC) vs. gates + SDF + activity(ETS) ?

     The first thing I notice is that your annotation is different yet you are using the same netlist. The SDF should not affect your toggle annotation as far as I can tell hence I would focus on understandig that first. Obviously until your annotation lines up, the rest of the numbers do not have much of a chance. Same netlist and same activity information should produce the same annotation regardless of tools or additional files read. Then start peeling the onion on power numbers

     gh-

Reply

  •  HI leez2006,

     not sure what you are trying to compare. Is it

     gates + activity(RC) vs. gates + SDF + activity(ETS) ?

     The first thing I notice is that your annotation is different yet you are using the same netlist. The SDF should not affect your toggle annotation as far as I can tell hence I would focus on understandig that first. Obviously until your annotation lines up, the rest of the numbers do not have much of a chance. Same netlist and same activity information should produce the same annotation regardless of tools or additional files read. Then start peeling the onion on power numbers

     gh-

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