Voltage Follower (Buffer):
This configuration is a special case of the non-inverting amplifier where all the output voltage is fed back to the inverting input by a straight connection (Rf = 0). The straight feedback connection has a voltage gain of 1 (no gain) so Vout = Vin.
The most important features of the voltage follower are its very high input impedance and very low output impedance which make it a nearly ideal buffer for interfacing high-impedance sources and low-impedance loads.
