Ask a question about complex pole

[wjxcom]

Hi all, if a transfers function H(s) of a Opreation Amplifer has a several complex poles, I don't know what information do these complex pole can experess?

 

[nxing]

which kind of information do you want?

 

[sunking]

you can use matlab to get the poles

 

[wjxcom]

I want to know if there have a complex pole, how to analyse the phase of this complex pole?

 

[fantaci]

I want to know if there have a complex pole, how to analyse the phase of this complex pole?

I think complex poles always exsit by pairs. So I think you`d better write the entire formula including the conjugate pole.

 

[jonw0224]

THINK ABOUT IT THIS WAY:

a + jb = A at angle θ, where θ = arctan(b/a)

1/(a + jb) = (1/A) at angle -θ.

Multiplying complex numbers adds the angles, dividing complex numbers subtracts the angle of the divisor from the angle of the dividend.

fantaci, is correct however, that complex poles ALWAYS APPEAR IN CONJUGATE PAIRS, so your equation (2) never happens in real systems. You can for academic interests find the angle of H. You can rewrite (2) as:

H = A(a+jb)/(a+j(w+b))

the angle of H = angle of (a+jb) minus the angle of (a + j(w+b)).