Differential amplifier

A differential amplifier is a type of electronic amplifier that amplifies the difference between two input voltages but suppresses any voltage common to the two inputs. It is an analog circuit with two inputs ${\displaystyle V_{\text{in}}^{-}}$ and ${\displaystyle V_{\text{in}}^{+}}$ and one output ${\displaystyle V_{\text{out}}}$, in which the output is ideally proportional to the difference between the two voltages:

${\displaystyle V_{\text{out}}=A(V_{\text{in}}^{+}-V_{\text{in}}^{-}),}$

where ${\displaystyle A}$ is the gain of the amplifier.

Single amplifiers are usually implemented by either adding the appropriate feedback resistors to a standard op-amp, or with a dedicated integrated circuit containing internal feedback resistors. It is also a common sub-component of larger integrated circuits handling analog signals.