Electronic Devices - Op-Amp Applications - Discussion
Discussion Forum : Op-Amp Applications - General Questions (Q.No. 18)
18.
Determine the value of Rf (assuming that all have the same value).
500 k
50 k
25 k
5 k
Discussion:
4 comments Page 1 of 1.
Roy said:
9 years ago
The 1st root of Rf is 50k.
Then the 2nd and 3rd gives the complex values.
Then the 2nd and 3rd gives the complex values.
Duy said:
1 decade ago
We have V0/Vin = (1+Rf/R1)*(-Rf/R2)*(-Rf/R3)
=>Rf = 50K
=>Rf = 50K
Nick said:
1 decade ago
@Bala.
Your answer is incorrect, since your Gain formula (1+Rf/R1) is only applicable for the first stage which is represented as non-inverting op-amp. The other two stages are inverting op-amps and Gain of each of them is equal to -Rf/Ri.
Your answer is incorrect, since your Gain formula (1+Rf/R1) is only applicable for the first stage which is represented as non-inverting op-amp. The other two stages are inverting op-amps and Gain of each of them is equal to -Rf/Ri.
(1)
Bala said:
1 decade ago
The ans is wrong.
solution: opamp are connected cascade and Rf,R1 are similar value.
stages are 3. so 3*(1+Rf/R1)Vi = Vo
3*(1+Rf/10)30mv =4.5V
Rf = 490 KilloOhm
solution: opamp are connected cascade and Rf,R1 are similar value.
stages are 3. so 3*(1+Rf/R1)Vi = Vo
3*(1+Rf/10)30mv =4.5V
Rf = 490 KilloOhm
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