[sdiy] Filter terminology question

[Ethan Duni]

> Whilst we're on the topic, does anyone understand how to compute the
> cutoff frequency and Q from a given transfer function?

Those two terms are not necessarily well defined for an arbitrary transfer
function. If the transfer function is known to be lowpass or highpass, the
cut-off frequency is usually defined to be the frequency at which the
magnitude response drops to 3dB below the passband value. Although you could
probably come up with a meaningful definition for "Q" when the transfer
function is a bandpass, it's really more of a circuit parameter than a
transfer function parameter.

Ethan