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Browse Prior Art Database

Programmable Magnetoresistive Arm Electronics Performance for Disk Drives

IP.com Disclosure Number: IPCOM000114595D
Original Publication Date: 1995-Jan-01
Included in the Prior Art Database: 2005-Mar-29
Document File: 2 page(s) / 37K

Publishing Venue

IBM

Related People

Kerwin, GJ: AUTHOR [+2]

Abstract

A method for providing varying electronic noise performance in a disk drive preamplifier is disclosed. The degree to which electronic noise can be minimized in an amplifier decreases with decreasing power supply voltage. This preamplifier provides reoptimization of some of the circuit elements to reduce the electronic noise as the headroom is expanded with higher available power supply voltage.

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This is the abbreviated version, containing approximately 100% of the total text.

Programmable Magnetoresistive Arm Electronics Performance for Disk
Drives

      A method for providing varying electronic noise performance in
a disk drive preamplifier is disclosed.  The degree to which
electronic noise can be minimized in an amplifier decreases with
decreasing power supply voltage.  This preamplifier provides
reoptimization of some of the circuit elements to reduce the
electronic
noise as the headroom is expanded with higher available power supply
voltage.

      The Figure shows a simplified diagram of a magnetoresistive
(MR) read preamplifier front-end stage.  Resistor modifications that
can be made to alter the electronic noise contribution of the
amplifier through selective "trimming" are shown as R3, R4, and RE2
in the Figure.  Removing a portion of the resistance, via any
available trimming technique, allows the use of a lower value of
positive supply voltage (VCC), at the expense of elevated
preamplifier
electronic noise.

      Conversely, if a higher value of VCC is available, the
resistances can be modified to use this voltage to provide a
reduction in preamplifier electronic noise.

      The reference voltage, which sets the MR element voltage as
well as the disk stack voltage is labeled VBIAS.  Since this voltage
is divided from VCC, the headroom to increase the resistances will be
automatically distributed between the preamp and the I Bias source.