Patent ID: 8310308

Claim:
An apparatus comprising: an input circuit having a first pair of differential output terminals and that provides a common-mode current; and an output circuit having: a second pair of output terminals; a first amplifier that is coupled to the first and second pairs of output terminals and that includes a resistor network; an second amplifier that is coupled to the resistor network so as to generate a control voltage from a sensed common-mode and a reference voltage; a first common-mode feedback circuit that is coupled the second amplifier so as to receive the control voltage and that is coupled to provide a first feedback current to the resistor network when the common-mode current is less than a predetermined threshold; and a second common-mode feedback circuit that is coupled to the second amplifier so as to receive the control voltage and that is coupled to provide a second current to the first pair of differential output terminals when the common-mode current is greater than a predetermined threshold.