In a practical op-amp circuit, the closed-loop gain is mainly set by which components?

In a practical op-amp circuit, the closed-loop gain is mainly set by which components?

• A. Power supply rails
• B. External components of the feedback network
• C. Internal compensation
• D. Input bias currents

Answer: (B)

The main thing setting the closed-loop gain in a practical op-amp circuit is the external feedback network. With negative feedback, the op-amp drives its output so that the portion of the output fed back to the input matches the input signal as closely as possible. The ratio of the feedback network elements fixes how much of the output is fed back, which determines the gain. For common configurations, this shows up as simple relationships like the output-to-input ratio being -Rf/Rin in an inverting setup or 1 + Rf/Rin in a non-inverting setup. The power supply rails mainly limit how large the output can swing, not the exact linear gain. Internal compensation shapes the frequency response and stability (bandwidth and phase margin) but does not set the DC gain in a well-behaved, linear region. Input bias currents mainly introduce small offsets rather than change the gain itself, though they can cause output offsets if the source impedances are mismatched. So, the external components of the feedback network are what fix the closed-loop gain in practice, provided the op-amp remains within its linear operating range.

The main thing setting the closed-loop gain in a practical op-amp circuit is the external feedback network. With negative feedback, the op-amp drives its output so that the portion of the output fed back to the input matches the input signal as closely as possible. The ratio of the feedback network elements fixes how much of the output is fed back, which determines the gain. For common configurations, this shows up as simple relationships like the output-to-input ratio being -Rf/Rin in an inverting setup or 1 + Rf/Rin in a non-inverting setup.

The power supply rails mainly limit how large the output can swing, not the exact linear gain. Internal compensation shapes the frequency response and stability (bandwidth and phase margin) but does not set the DC gain in a well-behaved, linear region. Input bias currents mainly introduce small offsets rather than change the gain itself, though they can cause output offsets if the source impedances are mismatched.

So, the external components of the feedback network are what fix the closed-loop gain in practice, provided the op-amp remains within its linear operating range.