Scott G O'Brien, 52Saint Paul, MN

6879456, Apr 12, 2005

Aug 15, 2002

10/219940

John D. Leighton - Anoka MN, US
Scott M. O'Brien - Eagan MN, US
Robert J. Wimmer - Hastings MN, US
Nameeta Krenz - Carver MN, US
Carl F. Elliott - Eden Prairie MN, US
Michael J. O'Brien - St. Paul MN, US
Cameron C. Rabe - Inver Grove Heights MN, US

Agere Systems Inc. - Allentown PA

G11B005/02

360 68, 360 67, 360 53, 360 46

A write driver circuit selectively provides a write current through a write head in first and second opposite directions. The write driver circuit is connected to the write head through an interconnect. The write driver circuit provides an incident write current signal through the interconnect to the write head, and also provides a reflection cancellation signal through the interconnect to the write head. In an exemplary embodiment, the incident write current signal is provided by providing an incident voltage signal across the write head, and the reflection cancellation signal is provided by providing a reflection cancellation voltage signal across the write head. In an exemplary embodiment, the reflection cancellation signal is a delayed and filtered version of the incident write current signal that cancels a reflected signal that is reflected at the interface between the interconnect and the write head due to impedance mismatching.

7019923, Mar 28, 2006

Apr 22, 2003

10/420236

John D. Leighton - Anoka MN, US
Hao Fang - Savage MN, US
Michael J. O'Brien - St. Paul MN, US
Scott O'Brien - Eagan MN, US
Cameron C. Rabe - Inver Grove Heights MN, US

Agere Systems Inc. - Allentown PA

G11B 5/09

360 46, 360 68, 330252, 327110

A pre-amplifier, a Thevenin writer and a disk drive employing transistors having a breakdown voltage below a circuitry operating voltage. In one embodiment, the pre-amplifier includes an emitter-follower transistor pair couplable to a power supply and a differential transistor pair, having a collector-emitter breakdown voltage below a voltage of the power supply, that receives current from, and controlled by, the emitter-follower transistor pair.

7339760, Mar 4, 2008

Sep 30, 2004

10/955775

Jeffrey A. Gleason - Burnsville MN, US
John D. Leighton - Anoka MN, US
Scott M. O'Brien - Eagan MN, US

Agere Systems Inc. - Allentown PA

G11B 5/02

360 67, 360 66, 360 68, 360 46

A preamplifier circuit is connected to a transducing head, and has integrated bias circuitry and offset recovery circuitry. The offset recovery circuitry is activated in response to a transition from write mode to read more to provide an output signal representative of a signal across the transducing head. The bias circuitry is driven by the output signal of the offset recovery circuitry to bias the transducing head.

7630159, Dec 8, 2009

May 27, 2005

11/140262

Scott M. O'Brien - Bloomington MN, US
Michael P. Straub - Longmont CO, US
Jeffrey A. Gleason - Burnsville MN, US
Nameeta Krenz - Carver MN, US
Arvind Aemireddy - Irving TX, US

Agere Systems Inc. - Allentown PA

G11B 5/03

360 66, 360 46, 360 67, 360110, 360313

An apparatus and method for determining a resistance of a magneto-resistive head. A current drawn by the head, in response to a fixed bias voltage across the head, is converted to a zero temperature coefficient current such that when supplied to a resistor connected to an input terminal of a comparator the effects of variations in the resistance value are avoided. An output signal of the comparator indicates the resistance of the magneto-resistive head.

7724460, May 25, 2010

Jan 13, 2005

11/034997

David J. Fitzgerald - Inver Grove Heights MN, US
Jeffrey A. Gleason - Burnsville MN, US
James P. Howley - Broomfield CO, US
Scott M. O'Brien - Eagan MN, US
Michael P. Straub - Longmont CO, US

Agere Systems Inc. - Allentown PA

G11B 5/02
G11B 5/03
G11B 5/09

360 67, 360 46, 360 66, G9B 5031, G9B 5026

A recording system employing a magneto-resistive (MR) element senses a resistance value of the MR element and generates one or more MR resistance (MRR) signal values based on the sensed MR element resistance value. The MRR signal values might be, for example, current or voltage values proportional or inversely proportional to the MR element resistance value. The MRR signal values might be employed to control one or more of: i) a unity gain bandwidth of a bias loop for the MR element, ii) an MR read head preamplifier low corner frequency, and iii) a slew rate across the MR element.

2004003, Feb 19, 2004

Aug 15, 2002

10/219948

John Leighton - Anoka MN, US
Scott O'Brien - Eagan MN, US
Robert Wimmer - Hastings MN, US
Nameeta Krenz - Carver MN, US
Carl Elliott - Eden Prairie MN, US
Michael O'Brien - St. Paul MN, US
Cameron Rabe - Inver Grove Heights MN, US

Agere Systems Inc.

G11B005/02

360/068000

A write driver circuit selectively provides write current through a write head in first and second opposite directions. First and second active devices are driven with first and second pre-drive signals. Third and fourth active devices are driven with third and fourth pre-drive signals. First and second pull-up resistances are provided respectively between the first and second active devices and a fixed voltage, and third and fourth pull-up resistances are provided respectively between the third and fourth active devices and the fixed voltage. A first capacitor is connected between the first active device and an intermediate point of the third pull-up resistance, and a second capacitor is connected between the second active device and an intermediate point of the fourth pull-up resistance.

2017018, Jun 29, 2017

Dec 28, 2015

14/979643

- Singapore, SG
Peter J. Windler - Fort collins CO, US
Bruce A. Wilson - San Jose CA, US
Jaydip Bhaumik - Longmont CO, US
Scott M. O'Brien - Mendota Heights MN, US
Jason P. Brenden - Woodbury MN, US
Jeffrey A. Gleason - Mendota Heights MN, US
Cameron C. Rabe - Mendota Heights MN, US

G11B 5/09

A storage system includes a magnetic write head, a magnetic storage medium, a channel circuit comprising a write data output, wherein the channel circuit is operable to process write data to be recorded on the magnetic storage medium by the magnetic write head, and a preamplifier operable to receive the write data from the channel circuit, wherein the preamplifier comprises a number of register pages configured to store pattern dependent write current characteristics for a variety of magnet lengths, and wherein the preamplifier is operable to retrieve the write current characteristics based on magnet lengths and to record data bits on the magnetic storage medium using the write current characteristics.

2014018, Jul 3, 2014

Dec 31, 2012

13/731693

- Milpitas CA, US
Xuemin Yang - Edina MN, US
Scott M. O'Brien - Eden Prairie MN, US

LSI Corporation - Milpitas CA

G11B 5/60

360 39

A fly height control circuit includes an input node to receive a digital control signal, an output node to output a control current to a resistive heater element to adjust a spacing between a read/write head and a surface of a storage medium, and control circuitry to process the digital control signal and generate the output control current based on the digital control signal. The control circuitry generates a first reference current based at least in part on the control current output from the output node. The control circuitry controls a slew rate of the first reference current to generate a slew rate controlled reference current. The control circuitry generates a second reference current based on a feedback voltage at the output node. The control circuitry compares the slew rate controlled reference current with the second reference current to adjust the control current output from the output node.