Filter Cuttoff Frequency Specification/Definiton

When designing a filter using a FILTERord(ie buttord) function you must specify the 'Passband corner (cutoff) frequency' and the 'Stopband corner frequency' (along with acceptable ripples) to get the lowest order and 'Cutoff frequency'. What are the formal specifications for these parameters, I can't find them anywhere. I believe the returned 'Cutoff frequency' is the the classical 3db frequency but that leaves the two inputs. I am designing analog filters. Thank You

Answer 1

[Andrey Kiselnikov]

Between pass band and stop band, there is an intermediate band, that you determine by ending of the passband and starting of the stopband. The width of this intermediate band determine the minimum required filter order to match these requirements (it is a very rough explanation).