Today I have heard, that is "impossible" to make low pass butterworth filter from cascading 1 order low pass filters(RC).

I am trying to discover is that true, but I can find little to none information on their difference.

Can you please explain to me, is that true, and if it is why. Thanks?

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    $\begingroup$ no. not with real coefficients. at a later time, i might be able to answer your question more fully. the issue is that the butterworth filter (and most other "interesting" filters that have enough "Q" or sharpness to do something useful) have poles that are complex conjugate. cascading 1st-order filters will only result in poles that are real. $\endgroup$ – robert bristow-johnson Nov 11 '14 at 16:45
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    $\begingroup$ Yes, it's impossible. The first-order filters have no "peaking" around the corner frequency. You need to combine 2nd-order filters, not 1st-order filters. $\endgroup$ – endolith Nov 11 '14 at 18:40

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