Cadence Virtuoso Result plot - slope change point

Dear asrf,

asrf said:

so lets say we have a curve and its slope suddenly changes at point X (x axis, i.e sweep variable) Is there any formula or script that I can use to return me the value of X point ?

Unless I am misunderstanding your question (always a possibility with me!), I believe the cross()  function will provide the x-axis value at the y value you specify. Hence, if you are plotting the slope and its value is positive and then becomes negative (i.e. its slope crosses 0.0), the syntax of the command might read:

cross(v(<your_slope_signal>" ?result "tran") "0" 1 "falling" nil nil  nil )

The cross() function with the arguments stated above finds the first x-axis value where <your_slope_signal> crosses 0.0 and returns this value. Alternative arguments to cross(0 will find all the x values where it crosses 0 as a waveform.

Did I understand your need and does this make sense to you arsf?

Shawn

thank you for your time. I am familiar with cross.

my slope does not change its sign. Imagine that is 10 then become 20 suddenly.

Dear asrf,

asrf said:

I am familiar with cross.

my slope does not change its sign. Imagine that is 10 then become 20 suddenly.

Then, in this case, if it crosses 20, then set the value of "0" to "20". If it only reaches the value of 20 and never exceeds 20 (i.e., never actually crosses 20) and was 10, set the value of "0" to some value between the 10 and 20 (potentially use the interpolate function argument if you like).

Shawn

Also, if it’s some threshold on the slope, you’d presumably use cross of the derivative (the deriv function) of the waveform. 

You just need to find some way to quantify what you mean by “sudden”.

Andrew

I found a way actually I ca define min and max slope and make cross point in the middle of them. Thank you this helped alot