What is the main purpose of differential amplification in instrumentation?

Differential amplification is primarily used to improve the quality of the signal being measured by effectively reducing noise and interference that can affect that signal. In this context, the technique focuses on amplifying the difference between two input signals while rejecting any common signals that are present in both. Such common signals often include noise or interference from external sources, which can distort the actual measurements of the signals of interest.

Utilizing a differential amplifier, the desired signal—such as a physiological signal from electrodes—can be distinctly amplified, while common-mode signals, or noise that affects both inputs equally, are minimized. This capability is crucial in instrumentation systems where accurate readings are required, particularly in environments with significant electrical noise.

The other options address different concepts: amplifying a single input signal does not capture the essence of differential amplification; enhancing common mode signals contradicts the fundamental goal of noise reduction; and filtering high-frequency signals pertains to a different function that does not specifically relate to the principle of differential amplification.