Exam-style question
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Which of the following best describes output saturation in a real op‑amp?.
- A.output voltage reaches the supply rails
- B.output voltage becomes zero
- C.output voltage is limited to half the supply voltage
- D.output voltage is unaffected by input
Model answer
What a good answer should say
- output voltage reaches the supply rails
Explanation
Why this works
Initial state: The op‑amp is powered from ±12 V rails and is fed a large input that would drive the output beyond the rails. Step‑by‑step execution: As the input increases, the op‑amp’s internal circuitry tries to increase the output voltage proportionally.
However, the output cannot exceed the positive or negative supply voltage. Final state: The output voltage is clamped at +12 V (or –12 V) and no longer follows the input.
Conclusion: When the output reaches the supply rails, the op‑amp is said to be in saturation.
Common mistake
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