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Using Montecarlo simulation for finding Rise and fall tile of a SETTLING waveform

RFQuery

 Dear All,

I want to do MONTE_CARLO simulation for my circuit for finding rise time and fall time.

The output is settling after 800u s.

I have to do some pre-processing before finding the last expression. The expressions I used as below.

But it did NOT work.

Can anybody tell how to find risetime and falltime of the waveform using MONTE-Carlo simulation if one needs some house-keeping processing of the waveform.

 .......

analysis('dc ?saveOppoint t  )
analysis('tran ?stop "1u"  ?errpreset "moderate"  ?maxstep "5p" 
        ?method "euler"  ?strobeperiod "5p"  )
desVar(      "frf" 6G    )
desVar(      "prf" -20    )
desVar(      "frf2" 6.1G    )
desVar(      "w" 20u    )
desVar(   "sigma" 3)
option(    'temp  "27.0"
    'iabstol  "1e-14"
    'vabstol  "1e-4"
)
saveOption( 'currents "selected" )
saveOption( 'save "all" )
temp( 27.0 )
monteCarlo( ?numIters "1" ?startIter "1"
    ?analysisVariation 'processAndMismatch ?sweptParam "None"
    ?sweptParamVals "27" ?saveData nil
    ?nomRun "yes" ?append nil
    ?saveProcessParams t
)
CLOCK_DUTY_PERIOD=2.5e-10
CLIP_START=0.8u
CLIP_END=0.9u

clip_I_P=clip( v("/MIXER_I_P" ?result 'tran) CLIP_START CLIP_END)
plot(clip_I_P)
MIN_VALUE=ymin(clip_I_P) + 0.02
MAX_VALUE=ymax(clip_I_P)- 0.03
UPPER_THRESOLD=MIN_VALUE + ( (MAX_VALUE-MIN_VALUE)*0.9 )
LOWER_THRESHOLD=MIN_VALUE + ( (MAX_VALUE-MIN_VALUE)*0.1 )
RISE_UPPER= cross( clip_I_P UPPER_THRESOLD 2 'rising )
RISE_LOWER= cross( clip_I_P LOWER_THRESHOLD 2 'rising )

monteExpr("RISE_TIME" "abs(RISE_UPPER-RISE_LOWER)")

monteRun()
Parents

  •  testmonte.scs fails because your function has:

             CLIP_START = CLIP_START + (CLOCK_DUTY_PERIOD*1.5)
            clip_I_P=clip( v("/MIXER_I_P" ?result 'tran) CLIP_START CLIP_END)

    if instead it was:

             CLIP_START = CLIP_START + (CLOCK_DUTY_PERIOD*1.5)
            clip_I_P=clip( signal CLIP_START CLIP_END)

    It would be OK. This is because in the testmonte.scs case, it can't use "/MIXER_I_P" to look up the signal name because that's in the "schematic" namespace, and since the netlist was not produced from a schematic, you don't have any mapping data (e.g. in the amap directory) to tell it the mapping between schematic and netlist names. If you recall, in the testmonte.scs file I had:

     export RISE_TIME=oceanEval("MyRiseTime(v(\"MIXER_I_P\" ?result 'tran) \
        8e-07 9e-07)") 

    (no leading slash). If I make the above change to the code, and then change the export statement to:

     export RISE_TIME=oceanEval("MyRiseTime(v(\"MIXER_I_P\" ?result 'tran) \
        2.5e-10 8e-07 9e-07)")

    Then it works fine. Note that I know it's definitely in the "then" branch of the if() because I tried multipling the abs() by 0.0, and the RISE_TIME ended up being 0.0 for all points.

    So almost certainly this is due to some failing of the cross() calls with your specific data. This shows the need to program defensively...

    Regards,

    Andrew.

     

Reply

  •  testmonte.scs fails because your function has:

             CLIP_START = CLIP_START + (CLOCK_DUTY_PERIOD*1.5)
            clip_I_P=clip( v("/MIXER_I_P" ?result 'tran) CLIP_START CLIP_END)

    if instead it was:

             CLIP_START = CLIP_START + (CLOCK_DUTY_PERIOD*1.5)
            clip_I_P=clip( signal CLIP_START CLIP_END)

    It would be OK. This is because in the testmonte.scs case, it can't use "/MIXER_I_P" to look up the signal name because that's in the "schematic" namespace, and since the netlist was not produced from a schematic, you don't have any mapping data (e.g. in the amap directory) to tell it the mapping between schematic and netlist names. If you recall, in the testmonte.scs file I had:

     export RISE_TIME=oceanEval("MyRiseTime(v(\"MIXER_I_P\" ?result 'tran) \
        8e-07 9e-07)") 

    (no leading slash). If I make the above change to the code, and then change the export statement to:

     export RISE_TIME=oceanEval("MyRiseTime(v(\"MIXER_I_P\" ?result 'tran) \
        2.5e-10 8e-07 9e-07)")

    Then it works fine. Note that I know it's definitely in the "then" branch of the if() because I tried multipling the abs() by 0.0, and the RISE_TIME ended up being 0.0 for all points.

    So almost certainly this is due to some failing of the cross() calls with your specific data. This shows the need to program defensively...

    Regards,

    Andrew.

     

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