Amplifier common-mode control method

A fully differential amplifier system with common-mode control having reduced sensitivity to random offsets and mismatches and improved common-mode loop bandwidth, comprising:

• a fully differential main amplifier configured to receiving input signals via a positive input port Vip and a negative input port Vin, and to generating output signals to a positive output port Vop and to a negative output port Von, wherein the main amplifier is provided with a continuous-time signal path feedback network, wherein a first terminal of a positive branch of the continuous-time signal path feedback network is connected to the positive input port Vip and a second terminal of the positive branch of the continuous-time signal path feedback network is connected to the negative output port Von, and a first terminal of a negative branch of the continuous-time signal path feedback network is connected to the negative input port Vin and a second terminal of the negative branch of the continuous-time signal path feedback network is connected to the positive output port Vop;
• and
• an common-mode control sub-amplifier, which is configured to sensing common-mode voltages of the fully differential main amplifier at a node Vcmip within a positive branch of the continuous-time signal path feedback network and at a node Vcmin within a negative branch of the continuous-time signal path feedback network, to comparing the common-mode voltage sensed at nodes Vcmin and Vcmip with a target reference voltage, and to regulating, depending on the result of the comparison, the output common-mode voltage via the continuous signal path feedback network.