Stephen M Gross

US Patent:

6751766, Jun 15, 2004

Filed:

May 20, 2002

Appl. No.:

10/152137

Inventors:

Daniel C. Guterman - Fremont CA
Stephen Jeffrey Gross - Cupertino CA
Geoffrey S. Gongwer - Los Altos CA

Assignee:

SanDisk Corporation - Sunnyvale CA

International Classification:

G11C 2900

US Classification:

714736

Abstract:

The quality of data stored in a memory system is assessed by different methods, and the memory system is operated according to the assessed quality. The data quality can be assessed during read operations. Subsequent use of an Error Correction Code can utilize the quality indications to detect and reconstruct the data with improved effectiveness. Alternatively, a statistics of data quality can be constructed and digital data values can be associated in a modified manner to prevent data corruption. In both cases the corrective actions can be implemented specifically on the poor quality data, according to suitably chosen schedules, and with improved effectiveness because of the knowledge provided by the quality indications. These methods can be especially useful in high-density memory systems constructed of multi-level storage memory cells.

US Patent:

6941412, Sep 6, 2005

Filed:

Aug 29, 2002

Appl. No.:

10/230657

Inventors:

Geoffrey S. Gongwer - Los Altos CA, US
Stephen J. Gross - Cupertino CA, US

Assignee:

SanDisk Corporation - Sunnyvale CA

International Classification:

G06F012/00

US Classification:

711103, 365202, 365227, 341 50, 380210, 713320

Abstract:

Methods and apparatus for transforming data into a format which may be efficiently stored in a non-volatile memory are disclosed. According to one aspect of the present invention, a method for storing information of a first data format in a memory system includes generating statistics associated with the first data format, and transforming the information from the first data format to a second data format using the statistics. Once the information is transformed into the second data format, the information is stored into a memory. Storing the information in the second data format in the memory includes storing an identifier that identifies a transformation used to transform the information to the second data format. In one embodiment, costs associated with storing the information in the second data format are less than or equal to costs associated with storing the information in the first data format.

US Patent:

7237074, Jun 26, 2007

Filed:

Jun 13, 2003

Appl. No.:

10/461244

Inventors:

Daniel C. Guterman - Fremont CA, US
Stephen J. Gross - Cupertino CA, US
Shahzad Khalid - Union City CA, US
Geoffrey S. Gongwer - Los Altos CA, US

Assignee:

Sandisk Corporation - Milpitas CA

International Classification:

G12F 12/00

US Classification:

711156, 711103, 3651852, 36518503, 36518509

Abstract:

Tracking cells are used in a memory system to improve the read process. The tracking cells can provide an indication of the quality of the data and can be used as part of a data recovery operation if there is an error. The tracking cells provide a means to adjust the read parameters to optimum levels in order to reflect the current conditions of the memory system. Additionally, some memory systems that use multi-state memory cells will apply rotation data schemes to minimize wear. The rotation scheme can be encoded in the tracking cells based on the states of multiple tracking cells, which is decoded upon reading.

US Patent:

7266026, Sep 4, 2007

Filed:

Aug 9, 2005

Appl. No.:

11/201007

Inventors:

Geoffrey S. Gongwer - Los Altos CA, US
Stephen J. Gross - Cupertino CA, US

Assignee:

SanDisk Corporation - Milpitas CA

International Classification:

G06F 5/00

US Classification:

365201, 711156, 711100, 365227

Abstract:

Methods and apparatus for transforming data into a format which may be efficiently stored in a non-volatile memory are disclosed. According to one aspect of the present invention, a method for storing information of a first data format in a memory system includes generating statistics associated with the first data format, and transforming the information from the first data format to a second data format using the statistics. Once the information is transformed into the second data format, the information is stored into a memory. Storing the information in the second data format in the memory includes storing an identifier that identifies a transformation used to transform the information to the second data format. In one embodiment, costs associated with storing the information in the second data format are less than or equal to costs associated with storing the information in the first data format.

US Patent:

7360136, Apr 15, 2008

Filed:

Jun 10, 2004

Appl. No.:

10/866554

Inventors:

Daniel C. Guterman - Fremont CA, US
Stephen Jeffrey Gross - Cupertino CA, US
Geoffrey S. Gongwer - Los Altos CA, US

Assignee:

Sandisk Corporation - Milpitas CA

International Classification:

G01R 31/28
G06F 11/00

US Classification:

714736, 714763

Abstract:

The quality of data stored in a memory system is assessed by different methods, and the memory system is operated according to the assessed quality. The data quality can be assessed during read operations. Subsequent use of an Error Correction Code can utilize the quality indications to detect and reconstruct the data with improved effectiveness. Alternatively, a statistics of data quality can be constructed and digital data values can be associated in a modified manner to prevent data corruption. In both cases the corrective actions can be implemented specifically on the poor quality data, according to suitably chosen schedules, and with improved effectiveness because of the knowledge provided by the qualify indications. These methods can be especially useful in high-density memory systems constructed of multi-level storage memory cells.

US Patent:

7681094, Mar 16, 2010

Filed:

May 22, 2007

Appl. No.:

11/752024

Inventors:

Daniel C. Guterman - Fremont CA, US
Stephen J. Gross - Cupertino CA, US
Shahzad Khalid - Union City CA, US
Geoffrey S. Gongwer - Los Altos CA, US

Assignee:

Sandisk Corporation - Milpitas CA

International Classification:

G11C 29/00
G06F 13/00

US Classification:

714718, 711100

Abstract:

Tracking cells are used in a memory system to improve the read process. The tracking cells can provide an indication of the quality of the data and can be used as part of a data recovery operation if there is an error. The tracking cells provide a means to adjust the read parameters to optimum levels in order to reflect the current conditions of the memory system. Additionally, some memory systems that use multi-state memory cells will apply rotation data schemes to minimize wear. The rotation scheme can be encoded in the tracking cells based on the states of multiple tracking cells, which is decoded upon reading.

US Patent:

7760555, Jul 20, 2010

Filed:

May 22, 2007

Appl. No.:

11/752008

Inventors:

Daniel C. Guterman - Fremont CA, US
Stephen J. Gross - Cupertino CA, US
Shahzad Khalid - Union City CA, US
Geoffrey S. Gongwer - Los Altos CA, US

Assignee:

Sandisk Corporation - Milpitas CA

International Classification:

G11C 16/04

US Classification:

36518528, 36518503

Abstract:

Tracking cells are used in a memory system to improve the read process. The tracking cells can provide an indication of the quality of the data and can be used as part of a data recovery operation if there is an error. The tracking cells provide a means to adjust the read parameters to optimum levels in order to reflect the current conditions of the memory system. Additionally, some memory systems that use multi-state memory cells will apply rotation data schemes to minimize wear. The rotation scheme can be encoded in the tracking cells based on the states of multiple tracking cells, which is decoded upon reading.

US Patent:

7916552, Mar 29, 2011

Filed:

Apr 20, 2010

Appl. No.:

12/763569

Inventors:

Daniel C. Guterman - Fremont CA, US
Stephen J. Gross - Cupertino CA, US
Shazad Khalid - Union City CA, US
Geoffrey S. Gongwer - Los Altos CA, US

Assignee:

SanDisk Corporation - Milpitas CA

International Classification:

G11C 16/04

US Classification:

36518528, 36518503

Abstract:

Tracking cells are used in a memory system to improve the read process. The tracking cells can provide an indication of the quality of the data and can be used as part of a data recovery operation if there is an error. The tracking cells provide a means to adjust the read parameters to optimum levels in order to reflect the current conditions of the memory system. Additionally, some memory systems that use multi-state memory cells will apply rotation data schemes to minimize wear. The rotation scheme can be encoded in the tracking cells based on the states of multiple tracking cells, which is decoded upon reading.