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Calculator function to check conditions on 3 (or N) waveforms

DKaraca

Hello,

I have a question about the use of calculator functions.

As an output of an s-parameter (or ac) simulation, I have three custom waveforms a_w, b_w, c_w which are all functions of frequency, i.e.  a_w(f), b_w(f), c_w(f).

I would like to check these waveforms to see if there is any frequency point "f0" satisying:

1) a_w(f0)<0

2) b_w(f0)=0

3) c_w(f0)>0

without visual observation on the graph.

Is there a way to do this using cadence calculator?

My cadence version is IC6.1.7-64b.500.23.

Thanks in advance.

Parents

  • This is a barely tested bit of SKILL that I think does what you want. You'd presumably pass it mag(VF("a")) etc (the magnitude) because it won't handle complex data. It finds all the crossing points for where signal b crosses 0, and then finds the value of a and c at each of those points until it finds one that matches the condition you've asked for. 

    procedure(CCFfindF0(a b c)
  cond(
    (drIsWaveform(a)
      ; main logic for a single waveform
      let((zeroPoints)
        zeroPoints=cross(b 0.0 0 "either")
        car(exists(zeroPoint zeroPoints
          value(a zeroPoint)<0.0 &&
          value(c zeroPoint)>0.0
        ))
      )
    )
    (famIsFamily(a)
      famMap('CCFfindF0 a b c)
    )
    (t
      error("CCFfindF0: can't handle %L\n" a)
    )
  )
)

    You can add it as a function in the calculator by using the "fx" button in the Function Panel (from IC617 onwards) - you can then define the form (to set each of the three arguments as signals) and then having done that once, you can use the function in any future session, or in ADE.

    Regards,

    Andrew.

  • in reply to Andrew Beckett

    Hi Andrew,

    Thanks for your quick reply. This does exactly what I needed.

    I will have a look at the skill language manual to further improve it -> return 1 if conditions met, return 0 otherwise

    Regards,

    Denizhan

Reply Children
  • in reply to DKaraca

    As is, the function returns the first frequency if there's a match, or nil otherwise. You could change it to (and I didn't test this):

    procedure(CCFfindF0(a b c)
  cond(
    (drIsWaveform(a)
      ; main logic for a single waveform
      let((zeroPoints firstCross)
        zeroPoints=cross(b 0.0 0 "either")
        firstCross=car(exists(zeroPoint zeroPoints
          value(a zeroPoint)<0.0 &&
          value(c zeroPoint)>0.0
        ))
            if(firstCross then 1 else 0)
          )
        )
        (famIsFamily(a)
          famMap('CCFfindF0 a b c)
        )
        (t
          error("CCFfindF0: can't handle %L\n" a)
        )
      )
    )

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