Hello Everyone,

Is there a general definition of Q for lowpass filters?

For a bandpass filter, there is the definition, Q=wo/bw, where "wo" is the resonant frequency, and "bw" is the
bandwidth.

For second order filters, the filter transfer function has a standard form in its denominator, so Q can
be extracted.  For the same reason, each stage of the biquad has a clearly defined Q.

However, what about a third-order filter, e.g., Z21= K/(s^3+2s^2+2s+1), what is its Q, does it have any meaning?  Is
there some graphical way of finding it, e.g., amount of peaking, etc?

Thanks

frank