G
Guest
- Jan 1, 1970
- 0
I did get in troubles with my student project circuit below!
The purpose is to amplify difference between two inputs. Specifically, 20mV and 10mV are connected with input to get 1V at the last OpAmp's output.
The problem is when two input are grounded,the output offset voltage of OA1 and OA2 comes to saturation in reality. I attempted to find out what problem is but it doesn't make sense.
As I figured, I used a potentiometer to adjust the offset voltage because I thought the offset voltage is just 20-30 mV, but in fact, it wasn't.
What's the cause of this problem?
Here is my circuit on proteus.
(i knew one of my problems is positive feedback stronger than negative feedback so the output will result in saturation...But when I replace R4 by a new one with value R4=150k to make R2/R1<(R3+R4)/R5 aim to increase positive feedback..but the result is still unchanged)...Any one here can help me with it..Thanks in advance
The purpose is to amplify difference between two inputs. Specifically, 20mV and 10mV are connected with input to get 1V at the last OpAmp's output.
The problem is when two input are grounded,the output offset voltage of OA1 and OA2 comes to saturation in reality. I attempted to find out what problem is but it doesn't make sense.
As I figured, I used a potentiometer to adjust the offset voltage because I thought the offset voltage is just 20-30 mV, but in fact, it wasn't.
What's the cause of this problem?
Here is my circuit on proteus.
(i knew one of my problems is positive feedback stronger than negative feedback so the output will result in saturation...But when I replace R4 by a new one with value R4=150k to make R2/R1<(R3+R4)/R5 aim to increase positive feedback..but the result is still unchanged)...Any one here can help me with it..Thanks in advance
