hi everyone, I would like to know how to characterize an input filter for a switching regulator( i wulod suppress emi), I use a common mode inductance and two capacitances. Doing a simulation on ltspice I have this. what am I doing wrong?

 

hi gio,
Please post your asc file and any models, we can then compare results.
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thanks!! add .asc and library

 

hi gio,
Edited the AC range, also C5 ground.

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Thank you!! I made the changes you told me but the Vin is different why? Vout is equal

 

did you change any parameters in the generator?

 

hi,
That's is strange.?
Try my asc file, I have named it '2A'
Post what you see.
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Gen image.

 

i see this from your circuit

 

hi,
That looks OK.
I don't know why your plot is different, repost Your asc file and I will double check.
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here it is...i change resistance value...but i have the same thing ,vin start from -90db

 

i have this

 

hi gio,
Please repost your asc file.
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ok!! i set resistance to 100k like at the beginning

 

hi,
Using that asc , no modifications, this it what I see.

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the strange thing is that the vin is different but the vout is the same
can someone explain to me why? @Bordodynov

 

hi,
These are some of my settings.
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I see the capacitors have a resonant frequency of 2.5mhz.