bandwidth of amplifier

[electra]

greetings,
I wonder if anyone can tell me why the product of bandwidth and gain has to be constant in amplifier? whats makes the amplifier to have such characteristics?
thanks.

 

[(*steve*)]

Google suggests you ask Wikipedia.

 

[davenn]

Thats a handy graph Steve, not one I had the need to look for
thanks for the info

Dave N

 

[cj_elec_tech]

Although that graph is only valid for AC coupled amplifiers. DC coupled amplifiers are 'flat' right to the vertical axis.