What is the general function of a difference amplifier?

What is the general function of a difference amplifier?

• A. It converts a differential input into a single-ended output
• B. It amplifies only the common-mode component
• C. It filters the input signal
• D. It saturates at small inputs

Answer: (A)

A difference amplifier is designed to respond to the voltage difference between two inputs and produce an output that is proportional to that difference. In the common single-ended configuration, this means the circuit gives a signal referenced to ground that represents how much V+ differs from V−, effectively converting a differential input into a single-ended output. This setup also rejects signals that are the same on both inputs (common-mode), which is useful for extracting small differential signals in noisy environments. The idea captured here is that the primary role is to amplify the difference between the two inputs, not the common component, not to act as a filter, and not to saturate at small inputs.

A difference amplifier is designed to respond to the voltage difference between two inputs and produce an output that is proportional to that difference. In the common single-ended configuration, this means the circuit gives a signal referenced to ground that represents how much V+ differs from V−, effectively converting a differential input into a single-ended output. This setup also rejects signals that are the same on both inputs (common-mode), which is useful for extracting small differential signals in noisy environments. The idea captured here is that the primary role is to amplify the difference between the two inputs, not the common component, not to act as a filter, and not to saturate at small inputs.