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LPF question

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stoica adrian:
Hello,
I have two qestions, if you can help me.
What happens after you pass the 3db point of a LPF, and witch is the maximum ° that you can obtain with a LPF?

Bassman59:

--- Quote from: stoica adrian on July 13, 2018, 03:00:38 am ---Hello,
I have two qestions, if you can help me.
What happens after you pass the 3db point of a LPF,
--- End quote ---


Pass it from which side? To the right (increasing frequency) of the 3 dB point, the response increases towards unity, at which point it flattens out. To the left of the 3 dB point, the response decreases with a slope given by the number of poles in (the order of) the filter. One pole, your attenuation goes as 6 dB/octave. Two poles give an attenuation of 12 dB/octave, and so forth.


--- Quote ---and witch is the maximum ° that you can obtain with a LPF?

--- End quote ---

That too depends on the order of the filter.

Circlotron:
RC low pass filter output would approach 90 deg phase lag, I expect.
Probably never quite get there.

David Hess:
90 degrees maximum per pole or order.

Audioguru:
A single R and a single C makes a very poor filter. it rolls off at only 6dB (half the level) for each octave (10 times the frequency). Use an opamp or a few to make a multi-order active filter.

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