quality factor of lowpass filter

[gmajay123]

1)Quality factor for bandpass can be visualized as Fc/BW (central freq/bandwidth ).
What does Q mean for a low pass filter.

2)Is it just the 2nd order filters which have Q or even 1st order, 3rd order, higher order systems have a Q factor.

Can someone also post a link for a good refence on material covering how to draw the bode plots from transfer functions on a linear frequency scale.

 

[FvM]

Q factor is a property of the 2nd order filter building blocks respectively it's complex pole.

 

[LvW]

Q factor is a property of the 2nd order filter building blocks respectively it's complex pole.

Yes, exactly spoken: The Q-factor of a complex pole pair is defined using the angle between the negativ real axis of the complex s-plane and the vector directed to the pole: Q=1/(2•cosα).

In the BODE plot the magnitude response shows a certain amount of peaking for Q>0.5. In the time domain the step reponse shows ringing for Q>0.5 up to a continuous oscillation ("ringing" with constant amplitudes) for Q= ∞.