Architecture for a hard disk drive write amplifier circuit with damping control

Abstract

A write amplifier circuit in a magnetic storage system has a cross coupling circuit and an active damp circuit to supply an improved write current to the head writing the data onto the media within the magnetic storage system. The inclusion of the cross coupling circuit decreases a rise time and a fall time associated with the write current. The active damp circuit reduces the undershoot and ringing of the write current. Thus, the write amplifier circuit is suitable for high speed data storage writing applications requiring minimal distortion of the data written to a magnetic medium. The write amplifier circuit achieves these improvements in the waveform of the write current by incorporating circuit elements and using both a negative feedback path and a feedforward path. In particular, the cross coupling circuit provides a feedforward path within the write amplifier circuit to a first current which creates a second current that is proportional and greater than the first current such that the second current increases the write current available for the head. Similarly, the active damp circuit provides a negative feedback path from the output terminals of the write amplifier circuit to a third current which creates a fourth current that is proportional and greater than the third current such that the fourth current damps an undershoot and ringing associated with the write current.