Browse Prior Art Database

DC MR Preamplifier with Short Circuit Protection

IP.com Disclosure Number: IPCOM000106573D
Original Publication Date: 1993-Nov-01
Included in the Prior Art Database: 2005-Mar-21
Document File: 2 page(s) / 67K

Publishing Venue

IBM

Related People

Contreras, JT: AUTHOR [+4]

Abstract

In systems using nonlinear MR sensors, or in systems with MR sensors and thermal asperities, the dc component of the data signal is needed to detect the information without error. The best way to maintain this dc component without the corrupting effects of the large bias needed is to have a preamplifier as disclosed, which biases the MR sensor and eliminates only the effects of the bias (the dc voltage produced by the bias) from the resultant amplified version of the data signal.

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DC MR Preamplifier with Short Circuit Protection

      In systems using nonlinear MR sensors, or in systems with MR
sensors and thermal asperities, the dc component of the data signal
is needed to detect the information without error.  The best way to
maintain this dc component without the corrupting effects of the
large bias needed is to have a preamplifier as disclosed, which
biases the MR sensor and eliminates only the effects of the bias (the
dc voltage produced by the bias) from the resultant amplified version
of the data signal.

      The dc MR Amplifier can be divided into two major components.
The first component is an amplifier with at least one feedback loop
for dc and low frequency suppression.  The feedback control signal
associated with the feedback loop can be either a voltage or a
current.  This control signal is used to suppress the dc and low
frequency components of the information signal from the MR element.

The second major component is used to store the dc component of the
control voltage or current.  This control signal is used for
substantially eliminating the dc bias component of the information
signal which is due to the large bias needed for the MR element.  By
combining the first and second components of the dc MR Amplifier as
aforementioned, the track-and-hold circuitry stores the dc component
of the control signal in a "learn" mode; and then in a "read" mode,
this stored control signal is used by the amplifier circuitry to
replace t...