Agere Systems Inc.

Ronen Malka

David W Kelly

Jeffrey A Gleason

Scott M O'Brien

David Fitzgerald

Boris Briskin

Sally A Doherty

Arvind Reddy Aemireddy

Jason A Christianson

Jonathan P Comeau

William D Jensen

A method and apparatus for detecting signal peaks caused by a thermal asperity event in a magnetic recording media to reduce data reading errors introduced by the thermal asperity event. A common mode voltage is determined for differential signals representing data bits read from the magnetic recording media and a threshold voltage produced responsive to the common mode voltage. A comparator determines if either of the differential signals exceeds the threshold voltage, thereby indicating the occurrence of a thermal asperity event.

Variable threshold bipolar signal peak detector

A wafer containing integrated circuits having fuses which are selectively blown to trim circuit perimeters. The fuses are located adjacent scribe lanes, and fuse pads are located in the scribe lanes. The integrated circuits are trimmed by selectively energizing the fuse pads to blow selective fuses. When the integrated circuits are severed from the wafer, the fuse pads are severed from the integrated circuits.

Trimmed integrated circuits with fuse circuits

A magnetic data storage and retrieval system includes a magnetoresistive head, a resistor, a preamplifier circuit, a voltage measurement circuit, and a resistance calculation circuit. The preamplifier circuit is operably coupled to the magnetoresistive head and the resistor, and applies a first current to the magnetoresistive head and a second current to the resistor. The voltage measurement circuit measures a first voltage across the magnetoresistive head and a second voltage across the resistor. The resistance calculation circuit calculates a resistance of the magnetoresistive head based upon the first and second voltages.

Accurate resistance measurement for magnetoresistive head

A preamplifier system is provided for connection through an interconnect to a read head. The interconnect has a characteristic impedance associated therewith. The preamplifier system includes an amplifier circuit having an input for connection to the interconnect. The amplifier circuit amplifies an input signal carried from the read head through the interconnect, yielding an amplified input output signal. A feedback resistance is connected between the amplified output signal and the input of the amplifier circuit. The feedback resistance has a value selected to provide an effective input impedance of the preamplifier system to match the characteristic impedance of the interconnect.

Negative feedback impedance matched preamplifier

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Eden Prairie, MN, United States of America

Ronen Malka