What is the primary function of a buffer amplifier in digital electronics?

The primary function of a buffer amplifier in digital electronics is to isolate different parts of a circuit. Buffer amplifiers are designed to provide high input impedance and low output impedance, which effectively prevents loading effects between stages of a circuit. This means that they can receive a signal from one part of a circuit without affecting the performance of that part, while simultaneously driving another part of the circuit that may have different loading requirements.

By isolating the different components, buffer amplifiers help maintain signal integrity. They ensure that variations in load or impedance in one section do not adversely influence the signals being processed in another section. This is particularly important in digital circuits where signals need to be transmitted cleanly and reliably from one logic gate or circuit to another.

While buffer amplifiers can also have a slight amplification effect (which is why "to amplify the input signal" could seem relevant), their main purpose is not amplification but rather isolation and stabilization of the signal path between components. The other options, such as combining signals or filtering noise, do not accurately capture the defining characteristic of buffer amplifiers in a digital context.