Patent ID: 7852589
Filing Date: 2010-12-14
Classification: G11B

Abstract:
1. A disk drive comprising: a head that reads out data from a disk; a low cut filter that selectively uses a first cutoff frequency and a second cutoff frequency, and that cuts off part of a signal transmitted from the head; a waveform control filter that has a plurality of filtering coefficients, and that controls a waveform of a signal transmitted from the low cut filter, wherein the waveform control filter comprises a first FIR filter and a second FIR filter which has a smaller number of taps than the first FIR filter; and a filtering coefficient controller that controls the filtering coefficients of the waveform control filter in accordance with a signal from the waveform control filter and controls a filtering coefficient of the second FIR filter; wherein: when the low cut filter uses the first cutoff frequency, the filtering coefficient controller controls part of the plurality of the filtering coefficients at a first feedback gain level; and when the low cut filter uses the second cutoff frequency, the filtering coefficient controller controls the part of the plurality of the filtering coefficients at a second feedback gain level higher than the first feedback gain level.