Voltage follower (Buffer) Amplifier

The circuit configuration shown on Picture 1 is known as voltage follower or buffer amplifier. As we can see from the picture, the input signal is leaded at the positive input terminal of the operational amplifier, while the negative input terminal is directly connected to its output. This circuit do not amplifies the input voltage signal, it just leads the input to the output of the circuit and that's way this circuit is called voltage follower amplifier (the output follows the input) or buffer amplifier (the circuit buffers the input signal).

Picture 1: Voltage follower (Buffer) Amplifier

This configuration is closest to the non-inverting amplifier, where R1 is infinity and R2 = 0. Therefore, the gain is equal to 1 and the input impedance is infinity. So, this configuration elliminates loading, allowing a source with a relatively large Thevenin's resistance to be connected to a load with a relatively small resistance.