Electronics and Communication Engineering - Analog Electronics - Discussion

Discussion Forum : Analog Electronics - Section 3 (Q.No. 16)
16.
The inverting op-amp shown in the figure has an open loop gain to 100. The closed loop given is
-8
-9
-10
-11
Answer: Option
Explanation:

Applying KCL inverting node

.

Discussion:
9 comments Page 1 of 1.

Raju palakkunnu said:   1 decade ago
You are right if op-amp open loop gain is infinity (or too large), only then the virtual ground concept exist. But here the open loop gain is limited (100).

So we can't use that formula. The answer is D.

Komal said:   8 years ago
Formula for closed loop gain for inverting amplifier is:

Acl = -(Rf/R1)/(1+((1+Rf/R1)/Aol)),
Acl = -10/(1+(11/100),
= -9.

Shailesh said:   1 decade ago
We can't calculate it directly?

Because its inverting amplifier and its gain is -Rf/R1 = -10.

Mukund said:   8 years ago
Its answer would be option B ie -9.

This question is asked in gate 2001.

Anjana said:   7 years ago
Gain=A/(1+AB),
Here B= -1/10
Reciprocal of( -Rf/R1),
A=100.

Hariharan said:   2 years ago
I think the correct answer is -9.

Waqar said:   8 years ago
Yes, your are Right @Mukund.

Sunitha said:   8 years ago
Answer is option D. I agree.

Zulu Chungtia said:   6 years ago
-9 is the answer.
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