a question about the poles of filters

[lily1981216]

The poles of the biquad can be real or complex. Does the biquad with complex poles have more advantages than the biquad with real poles? Would somebody like to tell me? Thanks!

 

[LvW]

The poles of the biquad can be real or complex. Does the biquad with complex poles have more advantages than the biquad with real poles? Would somebody like to tell me? Thanks!

Filters with real poles have a very, very poor selectivity (Pole Q< 0.5) and can be built without any active part using only RC combinations.
Example: A band pass with Q=0.5 has a bandwidth which is 2*Fc (center frequency of 1 kHz with 2 kHz bandwidth).