GATE EC 2021 Set 1 — Question 20
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Analog Circuits → Op-Amp Circuits → Summing & Difference
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Question
Consider the circuit with an ideal OPAMP shown in the figure.
Assuming and , the condition at which equals to zero is
Correct answer
(A) V_(IN) = V_(REF)
Solution
The given circuit is a differential amplifier configuration. For an ideal op-amp, the voltages at the inverting and non-inverting terminals are equal ().
1.The voltage at the non-inverting terminal () is determined by the voltage divider formed by and the two resistors :
2.The voltage at the inverting terminal () is found using KCL at the node:
3.For , this simplifies to:
4.Substituting :
Assuming the standard balanced condition for such circuits where , we get:Thus, is the condition for .Continue learning with Success Tracker
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