A 500 Mb/s disk drive read channel in 0.25 /spl mu/m CMOS incorporating programmable noise predictive Viterbi detection and trellis coding

The hard disk drive (HDD) market continues its growth of more than 60% per year in area density. Use of higher spindle rotational speeds is also a HDD market trend over recent years. A combination of these two factors require read channel speed increases in excess of 40% annually to keep up with the HDD requirements. To keep pace with areal density curve, read channel speed alone is not enough. Besides data transfer rate, the effective number of user bits per magnetic transition is also increased. Therefore, more sophisticated signal processing and coding schemes are necessary. In fact, 3.5dB signal processing gain over the previous generation extended class IV partial response (EPR4) is measured at user bit density (UBD) of 3.0. The signal processing features of the 500Mb/s device are described.