A 300 Mb/s BiCMOS disk drive channel with adaptive analog equalizer

This complete disk drive read-write channel device combines the functions of channel equalization with analog Nyquist filtering. This chip includes circuitry performing the following read channel functions: Viterbi sequence detection; 24/25 rate coding; synchronous digital servo processing; write pre-compensation; clock synthesis; and support for multiple power modes. The channel performs maximum likelihood sequence detection to a new partial response target optimized for channel densities in the range 1.8-3.0b per PW50. Additional features of the chip include: two-stage thermal asperity correction; non-linear MR asymmetry correction; on-chip quality monitoring; dual mode-6b in data mode and 7b in servo mode-analog to digital converter (ADC); gain-insensitive zerophase restart circuitry; as well as analog and digital test features.