Browse Prior Art Database

Secondary Automatic Attenuator for Differentiator

IP.com Disclosure Number: IPCOM000114297D
Original Publication Date: 1994-Dec-01
Included in the Prior Art Database: 2005-Mar-28
Document File: 2 page(s) / 45K

Publishing Venue

IBM

Related People

Kurachi, K: AUTHOR [+2]

Abstract

Disclosed is a method of Automatic Attenuator for differentiator of read/write channel of the hard disk drive.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 76% of the total text.

Secondary Automatic Attenuator for Differentiator

      Disclosed is a method of Automatic Attenuator for
differentiator of read/write channel of the hard disk drive.

      The read/write channel consists of Automatic Gain Control
(AGC), Filter portion, Peak Detection (PD), Phase Lock Loop (PLL),
and Encoder/Decoder (ENDEC).

      The FILTER consists of Low Pass Filter (LPF), Equalizer, High
Pass FILTER (HPF), Cutoff control circuitry, Equalizer control
circuitry, and Secondary Automatic Attenuator (SAA) circuitry and the
SAA control circuitry.  The Figure shows an example of a block
diagram of SAA implemantation.

      The purpose of LPF is to reduce noise portion of read back
signal from PREAMP, and improve the signal to noise ratio.

      The Equalizer equalize the data signal which is lost by inter
symbol interference of written magnet of the disk.

      The LPF cutoff frequency and Equalizer boost value are depend
on the read back signal quality and/or recording density, and they
can controlled by register of read/write channel.

      The purpose of HPF is to differentiate filtered signal, and the
zero cross point represents the data point of read back signal
(differentiator).

      Disclosed is the implementationof Automatic Attenuator for
differentiator whose attenuator ratio is relative to the equalizer
control value, in order to keep the signal voltage swing of
differentiator same, if the boost value of equalizer is changed,...