A fully differential amplifier (FDA) is a DC-coupled high-gain electronic voltage amplifier with differential inputs and differential outputs. In its ordinary usage, the output of the FDA is controlled by two feedback paths which, because of the amplifier's high gain, almost completely determine the output voltage for any given input. In a fully differential amplifier, common-mode noise such as power supply disturbances is rejected; this makes FDAs especially useful as part of a mixed-signal integrated circuit.