If a class A differential amplifier is using only one of its two possible inputs, what will the output signal shape be?

When a class A differential amplifier uses only one of its two inputs, the output signal will closely resemble the signal present at that single input. This happens because differential amplifiers are designed to amplify the difference between two input signals. When only one signal is applied, the other input is typically connected to a reference point, such as ground.

In this scenario, the amplifier treats the ground reference (often zero volts) as the second input. Consequently, the output signal mirrors the waveform of the input signal, maintaining the same shape and characteristics, which is why the output will be exactly the same as the single input. The amplification factor will depend on the gain settings of the amplifier, but the fundamental shape will be preserved.

Therefore, the correct answer accurately describes the relationship between the input and output under these conditions.