One embodiment of the invention includes a system for writing data onto a magnetic disk. An output driver provides a first write current through a first output transistor in a first state and provides a second write current through a second output transistor in a second state. The first and second write currents can be provided to a disk write head to store opposing binary values, respectively. A bias current generator switches a first bias current between an intermediate voltage node in the second state and a first control node in the first state, and switches a second bias current between the intermediate voltage node in the first state and a second control node in the second state. The first and second bias currents can be provided to set a bias voltage at the first and second control nodes to bias the first and second output transistors, respectively.