buddypoor
|
Yes, thats right. The mentioned sqare root is the magnitude of the vector directed to the pole position in the s-plane - and it is called "pole frequency". But be careful, in the BODE diagram this pole frequency is NOT identical to the frequency where the transfer function magnitude has a (possible) peak resp. maximum. The exact formula is: Fpeak=Fp*sqrt[1-(1/2Qp^2)] ; Qp=pole Q. As you can see, for large Qp values both frequencies are very close to each other. I suppose, you know how Qp is defined in the s-plane, don't you?
Nevertheless, you can identify the pole frequency very easily: It is simply the frequency at which the 2nd order transfer function has a phase excursion of exactly 90 deg. This follows directly from the 2nd order transfer function - if expressed using Qp and wp=2*Pi*Fp.
|