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# LTspace EMC simulation

Hi team,

I tried to simulate EMC as per your technical article(https://www.analog.com/en/technical-articles/how-to-get-the-best-results-using-ltspice-part-1.html).

It shows a syntax error when adding the plot file .please check once and give a solution.

*I am attaching asc and PLT files FYR

cm_dm_Emc_Simu.zip

Parents
• I was able to run the AC analysis and have the plots for the vanalyzer1 and vanalyzer2.

Note that V1 value is changed to AC 1 for AC analysis.

• Hi John Kevin,

Thank you for the replay, I want CM DM separate graph(FFT analysis). please find the attached sample.

• Hi Anoop Varma m,

I tried this step by step procedures

1. Run the transient analysis and plot the vanalyzer1 and vanalyzer2

2. Go to VIEW menu and select FFT

3. Select OK

4. Select OK

Results to this

5. Add a plot pane and perform the mathematical operation to get the VCM and DCM

Final Result:

• Hi John Kevin,

The technical note- they mentioned the EN55022 Emission Limit Lines program, the same way I made the PLT file and added it to the Ltspice plot setting, but it shows a syntax error.

In the Below video, they explain the methods.

• Hi John Kevin,

The technical note- they mentioned the EN55022 Emission Limit Lines program, the same way I made the PLT file and added it to the Ltspice plot setting, but it shows a syntax error.

In the Below video, they explain the methods.

Children
• Thank you for sharing this link!

This is what I am able to generate so far.

I'm figuring out how to show the X-axis up to 30MHz.

Here is the *.plt

[FFT of time domain data]
{
Npanes: 1
{
traces: 2 {2,0,"(V(vanalyser2)+V(vanalyser1))*0.5*1e6"} {2,0,"(V(vanalyser2)-V(vanalyser1))*0.5*1e6"}
X: ('M',0,9000,0,30e+06)
Y[0]: (' ',0,0.0001,20,1e+006)
Y[1]: (' ',0,-450,50,100)
Log: 1 2 0
GridStyle: 1
PltMag: 1
Line: "dB" 4 0 (9000,316227.766016838) (50000,316227.766016838)
Line: "dB" 4 0 (50000,316227.766016838) (50000,316227.766016838)
Line: "dB" 4 0 (50000,316227.766016838) (150000,10000)
Line: "dB" 4 0 (150000,10000) (150000,1995.26231496888)
Line: "dB" 4 0 (150000,1995.26231496888) (500000,630.957344480193)
Line: "dB" 4 0 (500000,630.957344480193) (5000000,630.957344480193)
Line: "dB" 4 0 (5000000,630.957344480193) (5000000,1000)
Line: "dB" 4 0 (5000000,1000) (30000000,1000)
}
}

• Hi John Kevin,,

Thanks a lot, it is working now.

If you have  EN55032 setting, please share