jiangnancai said:
So what's the difference between the pole-zero doublet and zero-pole doublet?
If Wz>Wp,is it called pole-zero doublet,and vice versa?
Other question is that in my impression,Q factor is a factor to describe AC frequency response.But for settling time,it is a time domain response, so is it reasonable? Thanks
1.) In short: We have an "doublet" if we introduce a zero Fz1 and a pole Fp2 with the aim to cancel another pole Fp1 - and if Fz1 does not meet Fp1 exactly !
If Fz1>Fp1 the step response will have a "long tail" slightly above the final value and if Fz1<Fp1 the tail will be slightly below the final value.
2.) The Q factor of a pole pair is a measure for the ac response in the transition region around the pole frequency - and at the same time Q detrermines the step response in the time domain. For Q>0.5 we will have a an overshoot which increases and turns into ringing for higher Q values.
Does it help ?