Non-inverting differential amplifier with configurable common-mode output signal and reduced common-mode gain

A fully differential amplifier circuit (differential output) 150 includes first and second amplifiers (e.g. operational amplifiers, op-amps) 82, 84 configured to amplify a differential input signal with a non-inverting gain and a third operational amplifier 152 providing feedback. The first and second amplifiers respectively receive first and second components VIN1, VIN2 of the differential input signal at their non-inverting inputs and provide components of a differential output signal VOUT1, VOUT2 at their respective outputs 92, 98. The third op-amp has a non-inverting input coupled to the outputs of the first and second amplifiers, an inverting input receiving a reference signal Vcm, and an output coupled to at least one of the first and second amplifier inverting inputs. The third op-amp causes the first and second amplifiers to generate a common-mode output signal related to the reference signal. A method includes generating a differential output signal by amplifying a differential input signal with a non-inverting gain, loading a common-mode reference signal with an impedance no less than an input impedance of an amplifier, and generating a common-mode output signal by amplifying a common mode input signal with a gain less than unity. The amplifier circuit may be used in applications where a reduced common-mode gain is desirable in addition to high input impedance and low noise factor.