Stats

  • Locked Locked
  • Replies 25
  • Subscribers 63
  • Views 25758
  • Members are here 0
This discussion has been locked.
You can no longer post new replies to this discussion. If you have a question you can start a new discussion

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

  • Without seeing your data, it's really hard to debug (as I keep saying - customer support is the best avenue for this). The most likely scenario is that the cross() function is returning nil in some cases, and hence the subtraction is failing. Maybe if you do:

            RISE_UPPER= cross( clip_I_P UPPER_THRESOLD 2 'rising ) || 0.0
            RISE_LOWER= cross( clip_I_P LOWER_THRESHOLD 2 'rising ) || 0.0

    then it will succeed (albeit giving the wrong answers) but it might highlight where the problem is. If you save the waveform data from the monte carlo by adding ?savefamilyplots "yes" to the monteCarlo() call in your OCEAN script, then you can look at the waveforms for each point and check them after the event.

    The code change above says to either return the cross() value, or if cross returned nil, it will set RISE_UPPER or RISE_LOWER to 0.0.

    Regards,

    Andrew.

Reply

  • Without seeing your data, it's really hard to debug (as I keep saying - customer support is the best avenue for this). The most likely scenario is that the cross() function is returning nil in some cases, and hence the subtraction is failing. Maybe if you do:

            RISE_UPPER= cross( clip_I_P UPPER_THRESOLD 2 'rising ) || 0.0
            RISE_LOWER= cross( clip_I_P LOWER_THRESHOLD 2 'rising ) || 0.0

    then it will succeed (albeit giving the wrong answers) but it might highlight where the problem is. If you save the waveform data from the monte carlo by adding ?savefamilyplots "yes" to the monteCarlo() call in your OCEAN script, then you can look at the waveforms for each point and check them after the event.

    The code change above says to either return the cross() value, or if cross returned nil, it will set RISE_UPPER or RISE_LOWER to 0.0.

    Regards,

    Andrew.

Children
No Data

Community Guidelines

The Cadence Design Communities support Cadence users and technologists interacting to exchange ideas, news, technical information, and best practices to solve problems and get the most from Cadence technology. The community is open to everyone, and to provide the most value, we require participants to follow our Community Guidelines that facilitate a quality exchange of ideas and information. By accessing, contributing, using or downloading any materials from the site, you agree to be bound by the full Community Guidelines.