Patent ID: 7133229

Claim:
A magnetic recording disk drive comprising: a base; a spindle motor on the base; a magnetic recording disk rotatable by the spindle motor and having a recording layer of magnetizable material, the recording layer having a plurality of generally circular data tracks, each data track patterned into discrete data blocks of magnetizable material separated by nonmagnetic regions; a write head for magnetizing the data blocks; a write driver coupled to the write head for generating write pulses to the write head; a reference clock responsive to disk rotation for generating a reference clock signal; a phase-locked-loop (PLL) write-clock-generation circuit responsive to the reference clock signal and coupled to the write driver for controlling the timing of write pulses generated by the write driver, said circuit comprising a phase detector, a low-pass filter (LPF) and a voltage-controlled oscillator (VCO), the VCO output and the reference clock signal being input to the phase detector; and a rotational vibration sensor attached to the base, the vibration sensor output being summed with the phase detector output to provide a timing adjustment signal to the VCO.