Nameeta C Krenz

US Patent:

6879456, Apr 12, 2005

Filed:

Aug 15, 2002

Appl. No.:

10/219940

Inventors:

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

Assignee:

Agere Systems Inc. - Allentown PA

International Classification:

G11B005/02

US Classification:

360 68, 360 67, 360 53, 360 46

Abstract:

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.

US Patent:

7630159, Dec 8, 2009

Filed:

May 27, 2005

Appl. No.:

11/140262

Inventors:

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

Assignee:

Agere Systems Inc. - Allentown PA

International Classification:

G11B 5/03

US Classification:

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

Abstract:

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.

US Patent:

20040032684, Feb 19, 2004

Filed:

Aug 15, 2002

Appl. No.:

10/219948

Inventors:

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

Assignee:

Agere Systems Inc.

International Classification:

G11B005/02

US Classification:

360/068000

Abstract:

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.