Patent ID: 8174317

Claim:
A fully-differential amplifier circuit comprising: a differential amplifier configured to differentially amplify a first input signal and a second input signal serving as an input differential pair to generate a pair of a first intermediate signal and a second intermediate signal, the differential amplifier including a first input transistor configured to receive the first input signal, a second input transistor configured to receive the second input signal, a first load element arranged in series with the first input transistor, a second load element arranged in series with the second input transistor, and a current source commonly provided to the first input transistor and the second input transistor; a first class AB amplifier configured to amplify the first intermediate signal to generate a first output signal; and a second class AB amplifier configured to amplify the second intermediate signal to generate a second output signal, wherein the first output signal and the second output signal serve as an output differential pair, the first class AB amplifier amplifies the first intermediate signal with reference to a reference voltage adjusted by a first feedback signal that is a common mode component of the first output signal and the second output signal, and the second class AB amplifier amplifies the second intermediate signal with reference to a reference voltage adjusted by a second feedback signal that is a common mode component of the first output signal and the second output signal.