Ideal op-amp output impedance — conceptual check: In the idealized operational amplifier model used for closed-loop analysis, is the output impedance taken to be 0 Ω (i.e., an ideal voltage source behavior at the output)?

Introduction / Context:
Op-amp “ideal” models are intentionally simplified to make feedback analysis tractable. Among the assumptions—very high open-loop gain, infinite input impedance—is an output that behaves like an ideal voltage source with zero output impedance. This lets the amplifier maintain the commanded output voltage across a load without droop in the model.

Given Data / Assumptions:

• Ideal op-amp model for conceptual understanding.
• Closed-loop operation with negative feedback.
• No bandwidth or slew limitations considered.

Concept / Approach:
The ideal op-amp is modeled with Rout = 0 Ω so that the output node is stiff and unaffected by load current changes. In reality, Rout is small but not zero and is further reduced by feedback over frequency ranges where loop gain is high. For hand analysis and intuition building, assuming 0 Ω is standard and yields accurate first-order predictions within the linear region.

Step-by-Step Solution:

Verification / Alternative check:
Practical output impedance can be measured via small-signal load step tests; feedback reduces the open-loop Rout substantially within bandwidth. This aligns with the idealized 0 Ω concept used in introductory design.

Why Other Options Are Wrong:

• Incorrect: Conflicts with the standard ideal model assumption.
• Only true in open-loop operation: Open-loop output is not controlled; the assumption is a property of the ideal model, not of open-loop behavior.
• Only true above unity-gain frequency: Output impedance typically rises as loop gain falls at high frequency; the ideal 0 Ω is a simplifying assumption, not frequency-limited.

Common Pitfalls:
Assuming real outputs are always ideal; ignoring current limit, slew, and bandwidth that can cause droop or distortion under heavy loads.

Final Answer:
Correct