System and method for controlling common mode voltage via replica circuit and feedback control

A method, comprising:

• applying first and second components of an input differential signal to first and second control terminals of first and second input transistors of a first differential signal processing circuit, respectively;
• generating first and second components of a first output differential signal at first and second nodes between first and second load devices and the first and second input transistors, respectively;
• and
• controlling a first common mode voltage of the first output differential signal, including generating a first bias voltage for control terminals of first and second current-source transistors coupled in series with the first and second load devices and the first and second input transistors between first and second voltage rails, respectively, wherein the first bias voltage is generated from an input common mode voltage of the input differential signal.

An apparatus, comprising:

• means for applying first and second components of an input differential signal to first and second control terminals of first and second input transistors of a first differential signal processing circuit, respectively;
• means for generating first and second components of a first output differential signal at first and second nodes between first and second load devices and the first and second input transistors, respectively;
• and
• means for controlling a first common mode voltage of the first output differential signal including generating a first bias voltage for control terminals of first and second current-source transistors coupled in series with the first and second load devices and the first and second input transistors between first and second voltage rails, respectively, wherein the first bias voltage is generated from an input common mode voltage of the input differential signal.