Mallikarjunarao T wrote on Mar 19th, 2009, 3:22am:Hai,
I have small doubt, can you explain any one please. what is the relation between corner frequency and damping factor(critical,underdamped and overdamped) which one is better for design and at what values ??
Regards,
Mallikarjunarao T
There is NO relation between damping factor and 3-dB-corner frequency.
Take a lowpass of 2nd order as an example:
(1) the damping factor d determines if - and if yes - how large the overshoot of the step response will be and how long the settling time of the damped wave is. This factor is inversely proportional to the pole Q.
In the frequency domain the peaking of the transfer curve in the region of the pole frequency is proportional to the pole Q=1/2d
(2) The 3db-corner frequency is approximately equal to the pole frequency (for Q=0,7071 , d=0.7071 both are identical). This is the FREQUENCY of the damped step response, but has nothing to do with its duration (damping).
I forgot to recommend some values:
In case you like a good compromize between acceptable overshoot and no peaking in the 2nd order transfer curve d=0.707 (Butterworth approximation) is used very often. But any value around d=0.7 looks good.