Klaas B Klaassen

Author:

Klaas B. Klaassen

ISBN #:

0340501421

Author:

Klaas B. Klaassen

ISBN #:

0521471575

Author:

Klaas B. Klaassen

ISBN #:

0521477298

Author:

Klaas B. Klaassen

ISBN #:

0444423885

US Patent:

6400518, Jun 4, 2002

Filed:

Nov 1, 2000

Appl. No.:

09/702618

Inventors:

Jaydip Bhaumik - Rochester MN
Robert Andrew Kertis - Rochester MN
Klaas Berend Klaassen - San Jose CA
Raymond Alan Richetta - Rochester MN
Jacobus Cornelis Leonardus Van Peppen - San Jose CA

Assignee:

International Business Machines Corporation - Armonk NY

International Classification:

G11B 502

US Classification:

360 25, 360 46, 360 67

Abstract:

A circuit arrangement for correcting magneto-resistive head asymmetry includes a shift circuit which receives a read signal from a magneto-resistive head, and a polarity signal indicative of the polarity of any asymmetry of the read signal. Depending on the polarity of the asymmetry, the shift circuit either adds or subtracts a shift voltage to the read signal to produce a shifted read signal. The shift circuit outputs the read signal, the shifted read signal, and the shift voltage. First, second and third gain circuits are provided, which receive the read signal, the shifted read signal, and the shift voltage, respectively, and which each receive a respective control signal. The first, second and third gain circuits provide respective outputs amplified proportionally based on the respective control signals. Control circuitry provides the polarity signal to the shift circuit and the respective control signals to the first, second and third gain circuits, based on an amount of correction required. A common-mode-feedback circuit adjusts for changes in the common-mode caused by the waveform shaping.

US Patent:

6420910, Jul 16, 2002

Filed:

Apr 27, 1999

Appl. No.:

09/300564

Inventors:

John Thomas Contreras - San Jose CA
Paul Wingshing Chung - San Jose CA
Stephen Alan Jove - Watsonville CA
Klaas Berend Klaassen - San Jose CA
Jacobus Cornelis Leonardus Van Peppen - San Jose CA

Assignee:

International Business Machines Corporation - Armonk NY

International Classification:

H03K 522

US Classification:

327 77, 327560, 360 67

Abstract:

A method and system for providing a current-sensing preamplifier for use with a magnetoresistive sensor is disclosed. The method includes providing at least one input device coupled with the magnetoresistive sensor, providing a gain stage, and providing a feedback circuit. In a system aspect, the current-sensing preamplifier includes at least one input device. The at least one input device is coupled with the magnetoresistive sensor through an interconnect having a characteristic impedance. The at least one input device provides an input impedance for the current-sensing preamplifier. The current-sensing preamplifier also includes a gain stage coupled with the at least one input device and a feedback circuit coupled with the gain stage and the at least one input device. The feedback circuit provides at least one signal to the at least one input device. The at least one signal controls the input impedance based on at least one error signal.

US Patent:

6608736, Aug 19, 2003

Filed:

May 8, 2000

Appl. No.:

09/566375

Inventors:

Klaas Berend Klaassen - San Jose CA
Jacobus Cornelis Leonardus Van Peppen - San Jose CA

Assignee:

International Business Machines Corporation - Armonk NY

International Classification:

G11B 548

US Classification:

360246

Abstract:

An interconnect circuit for a readout channel front-end for a disk drive is disclosed that includes a forward line and a return line. Both the forward line and the return line have a first end and a second end. The first end of both the forward line and the return line is connectable to a magnetoresistive head. The second end of both the forward line and the return line is connectable to a single-ended preamplifier. The return line is arranged to be disposed between the forward line and a suspension for a magnetoresistive head. The forward trace has a first predetermined width and the return trace has a second predetermined width that can be the same or different from the first predetermined width. When the interconnect circuit is in a disk drive, the first end of the forward line is connected to a magnetoresistive head, and the second end of the forward line is connected to a single-ended preamplifier. Similarly, the first end of the return line is connected to the magnetoresistive head, and the second end of the return line is connected to the single-ended preamplifier.

US Patent:

6622252, Sep 16, 2003

Filed:

Apr 12, 2000

Appl. No.:

09/548358

Inventors:

Klaas Berend Klaassen - San Jose CA
Jacobus C. L. Van Peppen - San Jose CA

Assignee:

International Business Machines Corporation - Armonk NY

International Classification:

G06F 132

US Classification:

713320, 360 69, 713300

Abstract:

A portable computer includes a battery and a connection to an external power source, a two-speed data storage device being supplied power from one or more of the battery and the external power source, and a controller attached to the storage device. With the invention, when the storage device is powered by the internal battery, the controller not only reduces the rotation speed and the clock rate of the storage device, but also reduces the power consumption of the read/write electronics module inside the disk drive by lowering the power supply voltage for the write driver inside said module and lowering the tail currents for the amplifier stages in the readback amplifier inside said module. When the storage device is powered by an external power source, the controller will run the storage device at full speed and highest clock rate, and will provide the write driver inside the read/write electronics module with a power supply voltage high enough to accommodate the resulting higher data rate, and will provide tail currents in the amplifier stages of the readback amplifier high enough to accommodate the higher required bandwidth for the readback amplifier.

US Patent:

6671113, Dec 30, 2003

Filed:

Mar 6, 2001

Appl. No.:

09/798945

Inventors:

Klaas Berend Klaassen - San Jose CA
Jacobus Cornelis Leonardus van Peppen - San Jose CA

Assignee:

International Business Machines Corporation - Armonk NY

International Classification:

G11B 509

US Classification:

360 46, 360 68, 360 61, 327110

Abstract:

A method (and magnetic recording circuit structure) for write drivers to reduce the reversal time for the current through the inductive recording head, includes a write driver output stage providing a write signal output with a write signal source strength S , a magnetic write head with a write signal input essentially equal to strength S , and an interconnect circuit having a characteristic impedance Z coupled to the write signal output of the write driver output stage and the magnetic write head. The write driver output stage preferably includes a source-side termination circuit having output impedance Z , wherein the source-side termination circuit output impedance Z is substantially equal to Z and the source strength S of the write driver at the input of the interconnect circuit is temporarily enlarged after every polarity reversal of the write signal for a predetermined time duration t.

US Patent:

6859347, Feb 22, 2005

Filed:

Jan 4, 2001

Appl. No.:

09/756377

Inventors:

Richard Hsiao - San Jose CA, US
Klaas Berend Klaassen - San Jose CA, US
Edward Hing Pong Lee - San Jose CA, US
Timothy J. Moran - San Jose CA, US
Vladimir Nikitin - San Jose CA, US
Michael Paul Salo - San Jose CA, US
Samuel Wei-San Yuan - Saratoga CA, US

Assignee:

Hitachi Global Storage Technologies Netherlands, B.V. - Amsterdam

International Classification:

G11B005/39

US Classification:

360319

Abstract:

A magnetic transducer including an electrically conductive shield (ECS) which is disposed between the substrate and first magnetic shield is described. The ECS is preferably embedded in an insulating undercoat layer. The ECS is preferably electrically isolated from the magnetic sensor element and is externally connected to a ground available in the disk drive through the arm electronics. Two alternative ways for connecting the ECS to a ground are described. In one embodiment which is only effective with single-ended input type arm electronics, the ECS is connected to a ground through a via to a lead pad for the read head which is connected to the ground of the arm electronics. In a second and more preferred embodiment a separate lead pad is included on the head to allow the ECS to be connected to electronic or case ground when the head is installed in the arm. The extent of the ECS should be sufficiently large to cover the read head portion of the transducer, i. e. , from the edge of the first magnetic shield to the outer edges of the read contact pads, but should preferably not cover the write head pads.

US Patent:

7061706, Jun 13, 2006

Filed:

Mar 15, 2004

Appl. No.:

10/800931

Inventors:

John Thomas Conteras - Palo Alto CA, US
Klaas Berend Klaassen - San Jose CA, US
Jacobus Cornelis Leonardus van Peppen - San Jose CA, US

Assignee:

Hitachi Global Storage Technologies Netherlands B.V.

International Classification:

G11B 5/60

US Classification:

360 75

Abstract:

The spacing decrease between pole tips of a write element and a magnetic medium that is associated with the write element is linearly proportional to an input signal, such as an input voltage or current, to a slider flying height controller for a hard disk drive. The flying height controller includes a heater current controller and a multiplexer. The heater current controller receives the input signal and outputs a control current proportional to the input signal. The multiplexer couples the control current to a heating element associated with the write element on a selected slider body during a read operation. The heating element dissipates a power that is proportional to the control current and causes a decrease in the spacing between the pole tips of the write element and the magnetic medium that is linearly proportional to the control current and to the input signal.

US Patent:

7158348, Jan 2, 2007

Filed:

May 1, 2002

Appl. No.:

10/137145

Inventors:

A. David Erpelding - San Jose CA, US
Klaas Berend Klaassen - San Jose CA, US

Assignee:

Hitachi Global Storage Technologies Netherlands B.V. - Amsterdam

International Classification:

G11B 5/48

US Classification:

3602459, 3602443

Abstract:

An example of a multi-layer structure which may be used for supporting a transducer includes a support layer and an etch stop layer formed from a refractory metal on the support layer. A first electrically conducting layer of copper may be positioned on the etch stop layer. A dielectric layer may be provided on the first electrically conducting layer. A second electrically conducting layer of copper may be provided on the dielectric layer. The dielectric layer is positioned between the first electrically conducting layer and the second electrically conducting layer. The second electrically conducting layer may include a plurality of separate electrically conducting lines.