What is a major difference between AC and DC amplifiers?

The distinction between AC and DC amplifiers primarily revolves around their application and the types of signals they process. AC amplifiers are designed to amplify alternating current signals, which means they often include high-frequency filtering capabilities to eliminate unwanted noise and to ensure that the desired frequency components are accurately amplified. This filtering allows AC amplifiers to effectively manage a range of waveforms typically encountered in applications such as audio and radio frequency transmission.

In contrast, DC amplifiers are focused on direct current signals and do not incorporate the high-frequency filters seen in AC amplifiers. This absence of filtering enables DC amplifiers to maintain the integrity of low-frequency components and provides a direct representation of the input signal without the restrictions imposed by high-frequency filtering. As a result, DC amplifiers are employed in applications where the accurate representation of low-frequency signals, such as those used in sensor outputs or certain types of instrumentation, is crucial.

This insight into the role of filtering in AC amplifiers underscores why the correct answer highlights the presence of a high-frequency filter in AC amplifiers, setting them apart from DC amplifiers.