If you increase the feedback factor in a negative-feedback amplifier, what happens to closed-loop gain and bandwidth?

• A. Both gain and bandwidth increase.
• B. Gain decreases, bandwidth increases.
• C. Gain increases, bandwidth decreases.
• D. Both gain and bandwidth decrease.

Answer: (B)

Increasing the feedback factor in a negative-feedback amplifier lowers the closed-loop gain while widening the bandwidth. When you raise how much of the output is fed back (the feedback factor), the loop gain grows. The result is a smaller net amplification at low frequencies because the feedback subtracts more of the output from the input, pulling the overall gain toward the inverse of the feedback factor (roughly 1/β when loop gain is large). At the same time, the system’s dominant pole moves to a higher frequency, so the amplifier can respond to faster changes and the bandwidth increases. In many practical amplifiers, the gain-bandwidth product stays roughly constant: boosting loop gain reduces gain but boosts bandwidth so their product stays about the same.