Hi All
I am asked for the output voltage of the entire circuit (see attached).
The hint I get is to:
Find B, then ACL then VO
Where
B = the Feedback Network (i.e. a voltage divider) and X = the comparison element (compares input signal with output signal).
B is a voltage divider shown as R1 and R2 and it takes the output voltage, divides it, then feeds it into X.
My attempt:
Step 1 - Find B
B = output of feedback network / input applied to feedback network
So the formula for the output of a feedback network is:
Vo = Vi (R2 \ R1 + R2)
Vo = 0.03V (200 \ 9800 + 200) = 0.0006
Then
the input applied to the feedback network is:
Vin x Amplifier Gain = 0.03V x 500 = 15 V
Then
B = 0.0006 \ 15 = 0.00004
Step 2 - Find ACL
ACL = the gain of a closed loop.
AOL = the gain of an open loop (no voltage divider).
ACL = AOL \ 1 + BAOL
So
ACL = 15 \ 1 + 0.00004 x 15 = 15
Step 3 - Find Vo
Vo = voltage output
Okay, I am lost here. I already used the Vo formula in step 1 to get the voltage output of the feedback network (i.e. the voltage divider) so do I need to use it again?
I don't get it really. If Vin is 0.03 V why can't I simply multiply that with the amplifier gain of 500?
I suspect the divider circuit influences how you find the voltage of the entire circuit but I just can't see what formula to apply here for each of the 3 steps.
Any help much appreciated
I am asked for the output voltage of the entire circuit (see attached).
The hint I get is to:
Find B, then ACL then VO
Where
B = the Feedback Network (i.e. a voltage divider) and X = the comparison element (compares input signal with output signal).
B is a voltage divider shown as R1 and R2 and it takes the output voltage, divides it, then feeds it into X.
My attempt:
Step 1 - Find B
B = output of feedback network / input applied to feedback network
So the formula for the output of a feedback network is:
Vo = Vi (R2 \ R1 + R2)
Vo = 0.03V (200 \ 9800 + 200) = 0.0006
Then
the input applied to the feedback network is:
Vin x Amplifier Gain = 0.03V x 500 = 15 V
Then
B = 0.0006 \ 15 = 0.00004
Step 2 - Find ACL
ACL = the gain of a closed loop.
AOL = the gain of an open loop (no voltage divider).
ACL = AOL \ 1 + BAOL
So
ACL = 15 \ 1 + 0.00004 x 15 = 15
Step 3 - Find Vo
Vo = voltage output
Okay, I am lost here. I already used the Vo formula in step 1 to get the voltage output of the feedback network (i.e. the voltage divider) so do I need to use it again?
I don't get it really. If Vin is 0.03 V why can't I simply multiply that with the amplifier gain of 500?
I suspect the divider circuit influences how you find the voltage of the entire circuit but I just can't see what formula to apply here for each of the 3 steps.
Any help much appreciated
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