Exam-style question
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Which statement best explains why the output of a real op‑amp may saturate while an ideal op‑amp does not?.
- A.Real op‑amp has limited supply voltage, ideal has infinite supply
- B.Real op‑amp has finite output resistance, ideal has zero
- C.Real op‑amp has limited bandwidth, ideal has infinite
- D.Real op‑amp has non‑zero offset voltage, ideal has zero
Model answer
What a good answer should say
- Real op‑amp has limited supply voltage, ideal has infinite supply
Explanation
Why this works
Define an ideal op‑amp as having an infinite supply voltage, so its output can swing to any voltage. Define a real op‑amp as being powered by a finite supply voltage, limiting its output swing.
The key difference is the supply voltage limits: the real op‑amp can only output between its supply rails, leading to saturation when the desired output exceeds these limits. This applies when the input signal or gain drives the output beyond the supply rails.
Hence the correct explanation is that the real op‑amp has a limited supply voltage while the ideal op‑amp does not.
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