Fast Transient Burst Signal Filter

transient/burst

How can I suppress 4kV, 2.5kHz and 2kV, 5kHz burst signals?
I'm using three 1mH, 10nF LC filters but my circuit is still influenced, all digital lines in my circuit is changing.
How can I find the spectrum of the burst signal ? I want to see the signal in frequency domain to make proper filter.

Thanks

fast transient burst filter

How can I find the spectrum of the burst signal ?

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With digital spectrum analyser. probably . But in transcients are wide bandwith in general You can't use some notch filter to suppres them.

I think that you shoud first reexamine grounding, coupling and isolation of your digital circuit. With proper design you can significantly increase noise immunity.

Give us some detail, if you want further assitance.

A Fast transient burst individual pulse has a 5 ns rise time for a duration of 50ns.
The energy is weak but the resulting frequency spectrum is very wide with harmonics > 200MHz.
There is no doubt you would see that on a spectrum analyzer but that would be a little help.
You can also hear them with a simple AM radio receiver tuned in any SW frequency.
Dont forget that it is a Common Mode signal and that it will return to ground by the easiest way. You'd better dont let him choose its way.
It propagate using every little capacitive path. To fight it, an efficient ground plane and best equipotentiality as possible is the right way to go.

When filtering is necessary, usually a little capacitor to ground plane ( eg 1nF ) will do the job.


Good luck