An amplifier circuit includes a first stage that receives a signal input and a control input and that generates first stage outputs. A second stage that communicates with the first stage and the control input and that includes a current source drivers. Each of the current source drivers have a constant current source mode and a driver mode. The constant current source mode and the driver mode are selected based on the signal input and the control input. A comparator circuit compares current through the current source drivers with a reference current. A control circuit generates the control input based on the comparison.