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spectre input.cs : conditional equation in .measure (min of 2 measurements)

samung

Hello,

using spectre in batch mode, I am trying to define the following conditional equation, to measure a capacitance.
I would like to know how to get the minimum between two parameters: maxvbl and V0 in my case, using the .measure strategy ?

input.scs extract:

parameters I0=10e-06
parameters V0=1.0
...
save blo\<16\> gslo\<0\>
...
.measure tran maxvbl max v(blo\<16\>)
.measure tran trigger param= 'min(maxvbl:V0)' <- conditional equation
.measure tran meas_when_trigger when v(blo\<16\>)='trigger'
.measure tran dvbl deriv v(blo\<16\>) at='meas_when_trigger'
.measure tran cbl param='I0/dvbl'

I cannot use spectremdl or ocean, using .measure syntaxe is somewhat mandatory to solve this point.

Thanks a lot in anticipation for any help,

P.

Parents
  • Andrew Beckett

    I don't really understand why you can't use SpectreMDL for this, but the key problem is in your trigger calculation. You've used ":" instead of ",".

    //

    parameters I0=10e-6
    parameters V0=1.0

    Vn (s1 0) vsource type=sine freq=1M ampl=1.1

    tran tran stop=2u

    simulator lang=spice
    .measure tran maxvbl max v(s1)
    .measure tran trigger PARAM='min(V0,maxvbl)'
    .measure meas_when_trigger when v(s1)=trigger
    .measure tran dvbl deriv v(s1) at=meas_when_trigger
    .measure tran cbl param='I0/dvbl'

    For me with a ":" it gave a very clear error. With the above example I get:

    Measurement Name : transient1
    Analysis Type : tran
    cbl = 2.75439e-12
    dvbl = 3.63057e+06
    maxvbl = 1.09687
    meas_when_trigger = 1.81692e-07
    trigger = 1

    I can change V0 to 1.2 (say) and it still works (then the measurement is taken at the peak of s1).

    Regards,

    Andrew.

Reply
  • Andrew Beckett

    I don't really understand why you can't use SpectreMDL for this, but the key problem is in your trigger calculation. You've used ":" instead of ",".

    //

    parameters I0=10e-6
    parameters V0=1.0

    Vn (s1 0) vsource type=sine freq=1M ampl=1.1

    tran tran stop=2u

    simulator lang=spice
    .measure tran maxvbl max v(s1)
    .measure tran trigger PARAM='min(V0,maxvbl)'
    .measure meas_when_trigger when v(s1)=trigger
    .measure tran dvbl deriv v(s1) at=meas_when_trigger
    .measure tran cbl param='I0/dvbl'

    For me with a ":" it gave a very clear error. With the above example I get:

    Measurement Name : transient1
    Analysis Type : tran
    cbl = 2.75439e-12
    dvbl = 3.63057e+06
    maxvbl = 1.09687
    meas_when_trigger = 1.81692e-07
    trigger = 1

    I can change V0 to 1.2 (say) and it still works (then the measurement is taken at the peak of s1).

    Regards,

    Andrew.

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