How to know whether biasing circuit has frequency dispersion or not?

I am learning how to design an amplifer. And I read some book which stated that the bias circuit should not have any frequency dispersion of envelope impedance in order to minimize the memory effect. How can I know wherether my biasing circuit has frequency dispersion or not? What parameter should I measure, e.g. s-parameter or others, when I try to find out it is existed or not?