Doing conducted EMC scan in LTspice

[cupoftea]

Hi,

The following, in Fig 10, suggests that an FFT can be done with limit lines as shown in Fig 11....

https://www.analog.com/en/resources/technical-articles/how-to-get-the-best-results-using-ltspice-part-1.html

So, I can run our Buck simulation in LTspice. Then i can view the FFT for the EMC test voltage.
Thats no problem to there.
I can also open the .plt file that LTspice gives.
However, when i adjust it to contain the "lines" data so that the limit line can be drawn..
...i cant make LTspice "see" the .plt file any more. So it doesnt draw the limit lines
on the FFT.
Do you know what to do with the file shown in Fig 10?

 

[aliarifat794]

1. Run your Buck simulation in LTspice.
2. Generate the FFT plot for the EMC test voltage.
3. Save the plot data as a .plt file.
4. Open the .plt file and modify it to include the "lines" data as shown in Fig 10 of the article.
5. Save the modified .plt file.

After saving the modified .plt file, try reopening it in LTspice. If LTspice still doesn't recognize the file or doesn't draw the limit lines on the FFT plot, there might be an issue with the file format or the way you're saving it.