Editing Amplifier (section)

=== Inverting or non-inverting ===
{{Unreferenced section|date=December 2024}}
Another way to classify amplifiers is by the phase relationship of the input signal to the output signal.  An 'inverting' amplifier produces an output 180 degrees out of phase with the input signal (that is, a polarity inversion or mirror image of the input as seen on an [[oscilloscope]]). A 'non-inverting' amplifier maintains the phase of the input signal waveforms. An [[emitter follower]] is a type of non-inverting amplifier, indicating that the signal at the emitter of a transistor is following (that is, matching with unity gain but perhaps an offset) the input signal. Voltage follower is also non-inverting type of amplifier having unity gain.

This description can apply to a single stage of an amplifier, or to a complete amplifier system.