DC_SHELL, synopsys

Discussion in 'Hardware' started by perseo, Oct 11, 2007.

  1. perseo

    perseo

    Joined:
    Oct 9, 2007
    Messages:
    3
    Hi everybody,

    I´m working with Synopsys and my problem is my experiments don´t fit to theory. I´m measuring power and I don´t know what is failing if anything is really failing.

    Well, power is divided in two components
    1) Static
    2) Dynamic. And dynamic power is also divided in two components:
    2.1) Net switching power, due to charge and discharge of output capacitance
    2.2) Cell internal power

    Well, according to synopsys' (and I think everybody's) theory, net switching is more or less 90% of dynamic power, while cell internal power could reach a 30% peak in circuits with few transitions.

    However, my results are

    Global Operating Voltage = 2.5
    Power-specific unit information :
    Voltage Units = 1V
    Capacitance Units = 1.000000ff
    Time Units = 1ps
    Dynamic Power Units = 1mW (derived from V,C,T units)
    Leakage Power Units = 1mW


    Cell Internal Power = 644.8631 nW (66%)
    Net Switching Power = 329.3489 nW (34%)
    ---------
    Total Dynamic Power = 974.2120 nW (100%)

    Cell Leakage Power = 33.4626 nW


    I´m using two scripts for achieving power results.

    1)

    power_preserve_rtl_hier_names = true
    analyze -format vhdl -lib WORK "./prueba.vhd"
    elaborate prueba -arch "beh1" -lib WORK -update
    rtl2saif -output "prueba.RT.saif" -design "prueba"
    compile
    derive_timing_constraints

    2)

    sh "vcd2saif -i prueba.vcd -o prueba.saif -rtl prueba.RT.saif -strip prueba"
    elaborate prueba -arch "beh1" -lib WORK -update
    compile
    read_saif -input prueba.saif -instance top
    report_power
    report_area
    report_timing
    report_clock

    Well, the .vcd file (stimulus file) is obtained by simulating values with modelsim.

    One thing I´ve tried is varying bit by bit the inputs in the macro of modelsim, but I only get an increase of 15 nW in net switching power, what is very little.

    I don´t know what is happening. Any idea ??

    Thank you a lot
    perseo, Oct 11, 2007
    #1
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