Exam-style question
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When comparing the phase response of an ideal op‑amp to a real op‑amp, which statement is accurate?.
- A.Ideal op‑amp has constant phase shift of 180°, real has frequency‑dependent phase shift
- B.Both have constant 180° phase shift
- C.Ideal has frequency‑dependent phase shift, real constant
- D.Neither has phase shift
Model answer
What a good answer should say
- Ideal op‑amp has constant phase shift of 180°, real has frequency‑dependent phase shift
Explanation
Why this works
Define an ideal op‑amp as having a constant 180° phase shift between its input and output, regardless of frequency. Define a real op‑amp as having a phase shift that varies with frequency due to internal pole‑zero behaviour.
The key difference is that the ideal op‑amp’s phase shift is constant, while the real op‑amp’s phase shift changes with frequency. This difference matters when designing phase‑sensitive circuits or feedback networks.
Therefore the correct statement is that the ideal op‑amp has a constant 180° phase shift, whereas the real op‑amp’s phase shift is frequency‑dependent.
Common mistake
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