*fc*

, the center frequency, *BWp*

, the pass-band bandwidth and *BWs*

, the stop-band bandwidth, determine one of the five possible responses. For the *Ap*

or @*Asc*

) is given by *BWp*

, while for the *ω*_{c}

is given by the middle point of the transition width (e.g. *(BWp+BWs)/2*

for LP).With these in mind this is how the values of the three frequencies should be: for LP/HP *Analog Active* filters (Bessel, Butterworth and Chebyshev) and FIR_FS can achieve it. For that,

*fc=0*

, for BP/BS *fc>0*

, while the ratio between *BWp*

and *BWs*

determines whether it's a LP/HP, or a BP/BS. AP is a special case and only the all-pole *fc=0*

and *BWp=BWs>0*

.Satisfying the conditions is not enough, some care should be taken. E.g. if

*fc=1*

, *BWp=1k*

and *BWs=2k*

it's a BP case, but the results will probably be unsatisfactory.©Vlad, 2008 - 2015