Abstract: A disk drive is disclosed comprising a plurality of disk surfaces, and a plurality of heads actuated over the respective disk surfaces. In one embodiment, control circuitry generates a pulse duty cycle signal for one of the heads. In another embodiment, the control circuitry generates a first pulse width modulated signal for a first head, and a second pulse width modulated signal for a second head, wherein the second pulse width modulated signal comprises a phase offset from the first pulse width modulated signal.

Abstract: A method of selecting a dynamic fly height (DFH) control setting for a head in a disk drive is disclosed. The head is servoed over a disk, and a fly height measurement is generated for the head. A frequency component is extracted from the fly height measurement, and the DFH control setting for the head is adjusted in response to the extracted frequency component.

Abstract: Disclosed is a method for reducing spiral write time and clock reference drift while writing spiral reference patterns on a disk of a disk drive. The method includes: controlling a radial location of a head for writing a first band of tracks near one of an outer diameter (OD) circumference of the disk or an inner diameter (ID) circumference of the disk and for writing a second band of tracks near the other of the OD circumference of the disk or the ID circumference of the disk, respectively, wherein a substantial majority of the tracks each include a plurality of servo sectors including a track number and a sync mark; measuring a distance between first and second reference center positions of reference center tracks of the first and second bands of tracks; and writing a spiral reference pattern therebetween.