Which statement best describes the function of a differential amplifier?

Which statement best describes the function of a differential amplifier?

• A. Record the voltages difference between the active input and ground
• B. Record the sum of the voltages of both inputs
• C. Record the differences in the voltages of two inputs
• D. Record identical voltages received by the inputs

Answer: (C)

A differential amplifier is built to compare two input signals and produce an output that reflects their difference, while ignoring signals that are common to both inputs. The output is proportional to the difference between the two voltages (Vout ∝ Vplus − Vminus), which is why it excels at rejecting noise or interference that appears on both lines. This distinction matters: if you reference one input to ground, you’re looking at a single-ended amplifier; if you try to add the inputs together, you’d be dealing with a summing configuration. When both inputs are the same, the output ideally cancels to zero. So the statement describing recording the differences in the voltages of two inputs best captures the function of a differential amplifier.

A differential amplifier is built to compare two input signals and produce an output that reflects their difference, while ignoring signals that are common to both inputs. The output is proportional to the difference between the two voltages (Vout ∝ Vplus − Vminus), which is why it excels at rejecting noise or interference that appears on both lines. This distinction matters: if you reference one input to ground, you’re looking at a single-ended amplifier; if you try to add the inputs together, you’d be dealing with a summing configuration. When both inputs are the same, the output ideally cancels to zero. So the statement describing recording the differences in the voltages of two inputs best captures the function of a differential amplifier.