Editing Buffer amplifier (section)

=== Op-amp implementation ===
[[Image:Block Diagram for Feedback.svg|thumb|Figure 2: A negative feedback amplifier|290px|left]] [[Image:Op-Amp Unity-Gain Buffer.svg|thumb|Figure 3. An [[op-amp]]–based unity gain buffer amplifier]] [[Image:Voltage follwer boosted 4clamp II.svg|thumb|A voltage follower boosted by a [[transistor]]; also can be seen as the "ideal transistor" without a base-emitter [[Forward bias|forward bias voltage drop]] on the input signal. This is the basic circuit of [[linear voltage regulator]]s]]
A [[1 (number)|unity]] gain buffer amplifier may be constructed by applying a full series [[negative feedback amplifier#Feedback and amplifier type|negative feedback]] (Fig. 2) to an [[op-amp]] simply by connecting its output to its inverting input, and connecting the signal source to the non-inverting input (Fig. 3). '''Unity gain''' here implies a ''voltage gain'' of one (i.e. 0 dB), but significant ''current gain'' is expected. In this configuration, the entire output voltage (β = 1 in Fig. 2) is fed back into the inverting input. The difference between the non-inverting input voltage and the inverting input voltage is amplified by the op-amp. This connection forces the op-amp to adjust its output voltage to simply equal the input voltage (V<sub>out</sub> follows V<sub>in</sub> so the circuit is named op-amp voltage follower).

The impedance of this circuit does not come from any change in voltage, but from the input and output impedances of the op-amp.  The input impedance of the op-amp is very high (1 [[Ohm|MΩ]] to 10 [[teraohm|TΩ]]), meaning that the input of the op-amp does not load down the source and draws only minimal current from it.  Because the output impedance of the op-amp is very low, it drives the load as if it were a perfect [[voltage source]].  Both the connections to and from the buffer are therefore [[impedance bridging|bridging]] connections, which reduce power consumption in the source, [[distortion]] from overloading, [[crosstalk]] and other [[electromagnetic interference]].