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Analog Adaptive Equalizer With Enhanced Self-Adjustability

IP.com Disclosure Number: IPCOM000101177D
Original Publication Date: 1990-Jul-01
Included in the Prior Art Database: 2005-Mar-16
Document File: 3 page(s) / 87K

Publishing Venue

IBM

Related People

Aoyagi, A: AUTHOR [+3]

Abstract

Disclosed is a new adaptive equalization technique of an analog read-back signal in a hard disk drive. It provides an enhanced self-adjustability for a pulse peak detector in a read/write channel.

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This is the abbreviated version, containing approximately 54% of the total text.

Analog Adaptive Equalizer With Enhanced Self-Adjustability

       Disclosed is a new adaptive equalization technique of an
analog read-back signal in a hard disk drive.  It provides an
enhanced self-adjustability for a pulse peak detector in a read/write
channel.

      This equalization has two advantages.  One is that it provides
the hard disk drive with self-adjustability which absorbs the
variation of bit-error-rate performance and optimizes that
performance for each head/disk/radius combination.  The other is that
it can automatically compensate the degradation of magnetic recording
characteristics of heads and disks used for a long time.

      It is well-known that an equalizer is one part of analog signal
processing of a pulse peak detector.  Its gain is an important
parameter which remarkably affects the bit error rate of the hard
disk drive.  The adaptive equalization procedure is as follows.  The
equalizer gain is changed on the basis of decision feedback, that is,
"re-read the data because an error is detected in data-stream at
error recovery process."  If an error is detected in a read mode, the
drive controller re-reads the data, changing the equalizer gain step
by step.  If the error is recovered by re-read, the drive controller
records that gain value into a table in RAM.  When the data at the
same location is accessed the next time, the controller will refer to
the table and use the updated gain value.  The drive system will
complete...