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How to extract a value from a self-defined plot, maybe using ocean script?

Alex Liao

Hey,

I have a plot which is gm/id (y-axis) Vs Id/(w/l) (x-axis) by doing a Parametric Analysis of sweeping Vgs.

I found in the result folder, it has lots of sub-folders named as Vg=0.111,..., Vg=0.555, Vg=0.666,..., Vg=0.999. Inside each of them, a /psf folder is there. This is reasonable as plenty of DC points are covered in the Parametric Analysis. Therefore all of those '/psf' result directories' are working together to compose a full plot by providing data and maybe do some interpolations.

I want to extract a value from this big plot and do not know how to do it.

Say, I can read when the X which is id/(w/l) = 5u, the Y which is gm/id = 10. But I want to get Y values by providing X values.

I am thinking since the X-Y in the big plot are one-to-one corresponded, if all the data are summarized in one place composing the complete plot or maybe in a big table, then giving a X and asking for a Y should be straightforward.

I am not quite sure if the waveVsWave will summarize all the data and provide a function to access it.

May refer to my previous post on how to do the plot on self-defined axis:

community.cadence.com/.../1343786

Any idea?

Regards,

Alex

Parents

  • Alex,

    I'm not entirely certain what you're referring to by "sampling points", but the simulator doesn't interpolate - it only writes out values that were solved. When you plot a waveform, it plots the actual points that were in the simulation results and draws a straight line between the points.

    Now, if you have two expressions and then plot one versus another, you will have pairs of points that match - both correspond to the same original x-axis and so the points you get then are still all simulated points (again, the lines shown between are a visual artefact to aid us poor humans who have trouble visualising things). You can always see the original points by selecting the trace (or traces) and doing Right Mouse->Trace Properties, turn on symbols and also "show all points" and you'll see the points. You can also pick that it plots  using points rather than joined lines.

    Now, when you use the value function, it will interpolate each curve in the family at that x-axis value - which may no longer correspond to a simulated point - and then plot those interpolated points versus the parameter value for each family member (so the x-axis points  you get in the value graph should correspond to the parameter points you picked).

    If you mean something else, you probably will need to give more details and show some pictures!

    Regards,

    Andrew.

Reply

  • Alex,

    I'm not entirely certain what you're referring to by "sampling points", but the simulator doesn't interpolate - it only writes out values that were solved. When you plot a waveform, it plots the actual points that were in the simulation results and draws a straight line between the points.

    Now, if you have two expressions and then plot one versus another, you will have pairs of points that match - both correspond to the same original x-axis and so the points you get then are still all simulated points (again, the lines shown between are a visual artefact to aid us poor humans who have trouble visualising things). You can always see the original points by selecting the trace (or traces) and doing Right Mouse->Trace Properties, turn on symbols and also "show all points" and you'll see the points. You can also pick that it plots  using points rather than joined lines.

    Now, when you use the value function, it will interpolate each curve in the family at that x-axis value - which may no longer correspond to a simulated point - and then plot those interpolated points versus the parameter value for each family member (so the x-axis points  you get in the value graph should correspond to the parameter points you picked).

    If you mean something else, you probably will need to give more details and show some pictures!

    Regards,

    Andrew.

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