# op amp design problem

Discussion in 'Homework Help' started by jack2010, Apr 14, 2010.

1. ### jack2010 Thread Starter New Member

Apr 14, 2010
2
0
hi guys i was hoping that maybe you could possibly help me with a particular question.
im new to electronics so my apologies if what i type doesnt make sense!
heres my assignment.

"you have a supply of operational amplifiers with a gain bandwidth product of 10^7 Hz and a good supply of resistors and capactiors. Design a system with an overall voltage gain of 4000 and a bandwidth of at least 20KHz . sketch a circuit which would implement this. suggest a use for your circuit"

any suggestions on how to tackle this would be great.

also if i have multiple op amps in succession im aware that the gain is multiplied. for example op amp A has gain of 40 and B 100, overall gain would be 4000. but what about the bandwidth?? is this the determined in the same way??

2. ### t06afre AAC Fanatic!

May 11, 2009
5,939
1,227
The bandwidth can be compered to a low pass filter function. So in your case the limiting factor will be gain stage with gain equal to 100. That will be weakest link in the chain so to speak

3. ### hgmjr Retired Moderator

Jan 28, 2005
9,030
218
If you want to share the gain-bandwidth evenly across the two amplifiers, one approach would be to take the square-root (since there are two stages) of the overall gain and then bump it up slightly to insure that the overall gain is both greater than the target value and at the same time the frequency response meets the minimum value.

hgmjr

4. ### jack2010 Thread Starter New Member

Apr 14, 2010
2
0
hi guys thanks for replies! after looking into this a bit further my best guess is this might be an active bandpass filter problem? with a low pass, then amplification stage and finally high pass stage?