I'm revising for my exam which is tomorrow, and am quite happy with the majority of the work however am totaly lost with this one:

An operational amplifier has open loop gain, AOL, of 5x10^5 and open loop bandwidth of 20 Hz. The operational amplifier is used in a negative feedback loop with feedback fraction B = 0.0016. Use the gain-bandwidth theorem to determine the bandwidth when the amplifier is used in such a manner.

I have no idea how to do this and would be greatfull is someone could explain

 

...orrrr just a little input? Hint? Anything : (

 

have you tried Google and gain bandwidth product?

 

Aol=5X10^5 = 500K and F_ol=20Hz
So after 20Hz Aol will be drop every 20 dB per decade.
So at F=10MHz you get Aol=1
So your opamp gain-bandwidth product i equal GBW=10MHz.
And now we can easily determine close loop bandwidth.
Fc = 10Mhz * 0.0016 = 16Khz
http://users.ece.gatech.edu/~mleach/ece3050/notes/OpAmps/opampbw.pdf

 

Thanks a lot Jony! That link really helps!