Exam-style question
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In an inverting amplifier with supply rails of ±12 V, if the calculated output voltage is +15 V, what will actually be observed at the output?.
- A.+15 V
- B.+12 V
- C.0 V
- D.-12 V
Model answer
What a good answer should say
- +12 V
Explanation
Why this works
Initial state: Supply rails V+ = +12 V, V− = -12 V. Calculated output Vout_calc = +15 V.
Step 1: Check if Vout_calc > V+. Step 2: Since +15 V > +12 V, the output is clamped to the positive rail.
Final state: Vout_actual = +12 V. Conclusion: The output cannot exceed the positive supply rail, so +12 V is observed.
Common mistake
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