For a standard inverting op-amp amplifier, which adjustment will decrease the magnitude of the closed-loop gain without changing topology or supply voltages?

Introduction:
Closed-loop gain control in the inverting amplifier relies on the resistor ratio. Knowing which component to adjust to reduce the magnitude of gain is fundamental for practical design and troubleshooting.

Given Data / Assumptions:

• Inverting configuration with input resistor Rin and feedback resistor Rf.
• Ideal op-amp behavior for gain calculation.
• We are interested in adjusting component values, not the input signal level.

Concept / Approach:
The inverting closed-loop gain magnitude is |Av| = Rf / Rin. To decrease |Av|, either reduce Rf or increase Rin. Changes to the input signal amplitude do not alter gain; they only change output level for a given gain.

Step-by-Step Solution:
1) Start with |Av| = Rf / Rin.2) To make |Av| smaller, increase the denominator (Rin) or decrease the numerator (Rf).3) Among the offered options, increasing the input resistor value directly increases Rin and reduces |Av|.4) Therefore, the correct choice is to increase the value of the input resistor.

Verification / Alternative check:
Example: If Rf = 10 kΩ and Rin = 1 kΩ, |Av| = 10. Doubling Rin to 2 kΩ reduces |Av| to 5, confirming the relationship.

Why Other Options Are Wrong:
Reducing input amplitude: Changes output level but does not change gain.

Increasing the feedback resistor: Increases |Av| because the numerator grows.

Removing the feedback resistor: Forces near open-loop conditions, making gain extremely large and uncontrolled.

Decreasing the input resistor: Reduces Rin, which increases |Av|.

Common Pitfalls:
Confusing signal amplitude with gain, or overlooking that the inverting gain depends purely on resistor ratio, not on op-amp open-loop gain within its linear range.

Final Answer:
increasing the value of the input resistor