Li C Du

US Patent:

6381085, Apr 30, 2002

Filed:

Jul 12, 1999

Appl. No.:

09/351736

Inventors:

Li Du - Denver CO
Mark Stephen Spurbeck - Superior CO
German Feyh - Boulder CO

Assignee:

Cirrus Logic, Inc. - Austin TX

International Classification:

G11B 5035

US Classification:

360 65, 375350

Abstract:

The invention includes disk drive circuitry, systems, and methods. The disk drive system comprises control circuitry and a disk device. The disk device stores data and transfers an analog signal representing the data. The control circuitry receives the analog signal, converts the analog signal into a digital signal, and transfers the digital signal. The control circuitry includes zero forcing circuitry and an adaptive filter. The zero forcing circuitry produces new coefficients for the adaptive filter. The control circuitry may also include an analog-to-digital converter, detector, decoder, and LMS circuitry. The analog-to-digital converter receives and samples the analog signal to generate a sampled signal. The adaptive filter shapes the sampled signal based on coefficients to produce an equalized signal. The detector detects binary data from the equalized signal, and the decoder decodes the binary data to generate the digital signal.

US Patent:

6490110, Dec 3, 2002

Filed:

Dec 19, 2000

Appl. No.:

09/740748

Inventors:

David E. Reed - Westminster CO
Stephen A. Turk - Longmont CO
Li Du - Broomfield CO

Assignee:

Cirrus Logic, Inc. - Austin TX

International Classification:

G11B 509

US Classification:

360 48, 360 53, 360 7708

Abstract:

Servo circuitry is disclosed that is configured to operate with a magnetic disk drive system. The servo circuitry is comprised of a first servo detector system, a second servo detector system, and a comparator. The first servo detector system and the second servo detector system each receive samples, taken from a read signal, that include servo data. The first servo detector system compares the samples to a plurality of servo codes to generate a first selected code. The second servo detector system compares a first shifted version of the samples to the plurality of servo codes to generate a second selected code. The comparator receives the selected codes and selects one of the selected codes. The selected code represents the servo data. The servo circuitry could also include a third servo detector system that operates on a second shifted version of the samples.

US Patent:

6819514, Nov 16, 2004

Filed:

Apr 30, 1996

Appl. No.:

08/640351

Inventors:

Richard T. Behrens - Louisville CO
Li Du - Boulder CO
William G. Bliss - Thornton CO
David E. Reed - Westminster CO
Mark S. Spurbeck - Louisville CO

Assignee:

Cirrus Logic, Inc. - Austin TX

International Classification:

G11B 5035

US Classification:

360 65, 360 46, 360 51, 375232

Abstract:

A sampled amplitude read channel for magnetic disk recording which asynchronously samples the analog read signal, adaptively equalizes the resulting discrete time sample values according to a target partial response, extracts synchronous sample values through interpolated timing recovery, and detects digital data from the synchronous sample values using a Viterbi sequence detector is disclosed. To minimize interference from the timing and gain control loops, the phase and magnitude response of the adaptive equalizer filter are constrained at a predetermined frequency using an optimal orthogonal projection operation as a modification to a least mean square (LMS) adaptation algorithm. Further, with interpolated timing recovery, the equalizer filter and its associated latency are removed from the timing recovery loop, thereby allowing a higher order discrete time filter and a lower order analog filter.

US Patent:

7929240, Apr 19, 2011

Filed:

Dec 18, 2008

Appl. No.:

12/337775

Inventors:

George Mathew - San Jose CA, US
Yuan Xing Lee - San Jose CA, US
Harley Burger - San Jose CA, US
Li Du - Broomfield CO, US

Assignee:

LSI Corporation - Milpitas CA

International Classification:

G11B 5/03
G11B 5/035

US Classification:

360 66, 360 65, 369 4717, 375254

Abstract:

Various embodiments of the present invention provide systems and methods for reducing head distortion. For example, various embodiments of the present invention provide storage devices that include a storage medium, a read/write head assembly, and an adaptive distortion modification circuit. The storage medium includes information that may be sensed by the read/write head assembly that is disposed in relation to the storage medium. The adaptive distortion modification circuit receives the information sensed by the read/write head assembly and adaptively estimates and implements a distortion compensation factor in the analog domain. In some instances of the aforementioned embodiments, the read/write head assembly includes a magneto resistive head. In such instances, the distortion compensation factor is designed to compensate for non-linear distortion introduced by the magneto resistive head.

US Patent:

8046666, Oct 25, 2011

Filed:

Aug 8, 2007

Appl. No.:

11/835706

Inventors:

Jongseung Park - Allentown PA, US
Andrei E. Vityaev - San Jose CA, US
Li Du - Broomfield CO, US

Assignee:

LSI Corporation - Milpitas CA

International Classification:

H03M 13/00

US Classification:

714774, 714795

Abstract:

A method of double detection in a perpendicular magnetic read channel is disclosed. The method generally includes the steps of (A) generating an intermediate signal by performing a first detection on an input signal of the perpendicular read channel, the first detection having a first error rate, (B) generating a statistics signal based on the intermediate signal, the statistics signal conveying noise statistics that depend on data in the input signal and (C) generating an output signal by performing a second detection on the input signal using the noise statistics to reduce a second error rate of the second detection compared with the first error rate, wherein the first detection is independent of the second detection.

US Patent:

20020069379, Jun 6, 2002

Filed:

Dec 5, 2000

Appl. No.:

09/730091

Inventors:

David Reed - Westminster CO, US
Stephen Turk - Longmont CO, US
Li Du - Broomfield CO, US

Assignee:

Cirrus Logic, Inc.

International Classification:

G06F011/00

US Classification:

714/054000

Abstract:

Servo circuitry is disclosed that is configured to operate with a magnetic disk drive system. The servo circuitry is comprised of a first servo detector system, a second servo detector system, and a comparator. The first servo detector system and the second servo detector system each receive samples, taken from a read signal, that include servo data. The first servo detector system compares the samples to a plurality of servo codes to generate a first selected code. The second servo detector system compares a first shifted version of the samples to the plurality of servo codes to generate a second selected code. The comparator receives the selected codes and selects one of the selected codes. The selected code represents the servo data. The servo circuitry could also include a third servo detector system that operates on a second shifted version of the samples. Alternatively, the first servo detector system, the second servo detector system, and the third servo detector system could each be programmed with different servo codes. The first servo detector system compares the samples to a plurality of first servo codes. The second servo detector system compares the samples to a plurality of second servo codes. The third servo detector system compares the samples to a plurality of third servo codes. The second servo codes and the third servo codes are shifted versions of the first servo codes. In either embodiment, the servo circuitry advantageously has improved phase shift tolerance.

US Patent:

63076942, Oct 23, 2001

Filed:

Feb 24, 1999

Appl. No.:

9/256695

Inventors:

Li Du - Denver CO
Mark Stephen Spurbeck - Superior CO
Richard Travis Behrens - Lafayette CO

Assignee:

Cirrus Logic, Inc. - Austin TX

International Classification:

G11B 509

US Classification:

360 46

Abstract:

The invention includes disk drive circuitry, systems, and methods. The disk drive system comprises control circuitry and a disk device. The disk device stores data and transfers an analog signal representing the data. The control circuitry receives the analog signal, converts the analog signal into a digital signal, transfers the digital signal, and biases an error signal. The control circuitry includes an analog-to-digital converter, adaptive filter, a decoder, and error signal circuitry. The analog-to-digital converter receives and samples the analog signal to generate a sampled signal. The adaptive filter shapes the sampled signal based on coefficients to produce a shaped signal. The decoder decodes the shaped signal to generate the digital signal. The error signal circuitry generates the biased error signal to adjust the coefficients in the adaptive filter.

US Patent:

59993553, Dec 7, 1999

Filed:

Apr 30, 1996

Appl. No.:

8/640410

Inventors:

Richard T. Behrens - Louisville CO
William G. Bliss - Thornton CO
Li Du - Boulder CO
Mark S. Spurbeck - Louisville CO
German S. Feyh - Boulder CO
Trent O. Dudley - Littleton CO

Assignee:

Cirrus Logic, Inc. - Fremont CA

International Classification:

G11B 5035
G11B 509

US Classification:

360 65

Abstract:

A sampled amplitude read channel for magnetic disk recording which asynchronously samples the analog read signal, adaptively equalizes the resulting discrete time sample values according to a target partial response, extracts synchronous sample values through interpolated timing recovery, and detects digital data from the synchronous sample values using a Viterbi sequence detector is disclosed. To minimize interference from the timing and gain control loops, the phase and magnitude response of the adaptive equalizer filter are constrained at a predetermined frequency using an optimal orthogonal projection operation as a modification to a least mean square (LMS) adaptation algorithm. Further, with interpolated timing recovery, the equalizer filter and its associated latency are removed from the timing recovery loop, thereby allowing a higher order discrete time filter and a lower order analog filter.