Magnitude of open-loop gain — op-amp fundamentals: Do operational amplifiers have very low open-loop gain, or is the open-loop gain typically very high (e.g., 10^5 or more at low frequency) before feedback sets the usable closed-loop gain?

Introduction / Context:The op-amp s power comes from its enormous open-loop gain (Aol), which allows negative feedback to precisely set a smaller, predictable closed-loop gain. Misstating the open-loop gain as “very low” inverts this fundamental idea and can lead to incorrect expectations about precision and linearity without feedback.

Given Data / Assumptions:

• Typical general-purpose op-amps exhibit Aol on the order of 10^5 to 10^6 at low frequency.
• Frequency compensation rolls off Aol with frequency, but DC/low-frequency Aol is still very high.
• Closed-loop gain is set by external networks under feedback.

Concept / Approach:High open-loop gain ensures that, under negative feedback, even tiny differential input errors produce the needed output to satisfy the feedback condition. This is why linear closed-loop gain can be accurate and largely resistor-ratio controlled. Therefore, the statement “an op-amp has very low open-loop gain” is false; the opposite is true.

Step-by-Step Solution:

Verification / Alternative check:Datasheets for classic op-amps (e.g., 741, 358, 5532) list typical DC open-loop gains from tens to hundreds of thousands, confirming the high Aol premise.

Why Other Options Are Wrong:

• Correct: Not correct; Aol is very high, not low.
• Only correct for unity-gain stable op-amps: Stability compensation does not reduce DC Aol to “very low.”
• Only correct above 1 MHz: Aol decreases with frequency, but not to “very low” at DC; the claim remains false.

Common Pitfalls:Assuming the specified closed-loop gain (e.g., 10 or 100) equals the device’s open-loop gain; overlooking how feedback leverages large Aol for accuracy.

Final Answer:Incorrect