Patents by Inventor Shahzad B. Khalid

Shahzad B. Khalid has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Patent number: 7301807
    Abstract: The present invention presents several techniques for using writable tracking cells. Multiple tracking cells are provided for each write block of the memory. These cells are re-programmed each time the user cells of the associated write block are written, preferably at the same time, using the same fixed, global reference levels to set the tracking and user cell programmed thresholds. The threshold voltages of the tracking cells are read every time the user cells are read, and these thresholds are used to determine the stored logic levels of the user cells. In one set of embodiments, populations of one or more tracking cells are associated with different logic levels of a multi-state memory. These tracking cell populations may be provided for only a subset of the logic levels. The read points for translating the threshold voltages are derived for all of the logic levels based upon this subset.
    Type: Grant
    Filed: February 22, 2005
    Date of Patent: November 27, 2007
    Assignee: SanDisk Corporation
    Inventors: Shahzad B. Khalid, Daniel C. Guterman, Geoffrey S. Gongwer, Richard Simko, Kevin M. Conley
  • Patent number: 6873549
    Abstract: The present invention presents several techniques for using writable tracking cells. Multiple tracking cells are provided for each write block of the memory. These cells are re-programmed each time the user cells of the associated write block are written, preferably at the same time, using the same fixed, global reference levels to set the tracking and user cell programmed thresholds. The threshold voltages of the tracking cells are read every time the user cells are read, and these thresholds are used to determine the stored logic levels of the user cells. In one set of embodiments, populations of one or more tracking cells are associated with different logic levels of a multi-state memory. These tracking cell populations may be provided for only a subset of the logic levels. The read points for translating the threshold voltages are derived for all of the logic levels based upon this subset.
    Type: Grant
    Filed: October 23, 2003
    Date of Patent: March 29, 2005
    Assignee: SanDisk Corporation
    Inventors: Shahzad B. Khalid, Daniel C. Guterman, Geoffrey S. Gongwer, Richard Simko, Kevin M. Conley
  • Patent number: 6807106
    Abstract: A memory system (e.g., memory card) offering hybrid density storage is disclosed. The memory system yields both high density storage and high performance operation. According to one aspect, certain data to be stored in the memory system can be stored in lower density storage so that it provides robust storage and/or high speed retrieval. Other data, which can be retrieved at moderate speeds or moderate robustness, can be stored to higher density storage in a space (area) efficient manner.
    Type: Grant
    Filed: December 14, 2001
    Date of Patent: October 19, 2004
    Assignee: SanDisk Corporation
    Inventors: Carlos Gonzales, Shahzad B. Khalid
  • Publication number: 20040105307
    Abstract: The present invention presents several techniques for using writable tracking cells. Multiple tracking cells are provided for each write block of the memory. These cells are re-programmed each time the user cells of the associated write block are written, preferably at the same time, using the same fixed, global reference levels to set the tracking and user cell programmed thresholds. The threshold voltages of the tracking cells are read every time the user cells are read, and these thresholds are used to determine the stored logic levels of the user cells. In one set of embodiments, populations of one or more tracking cells are associated with different logic levels of a multi-state memory. These tracking cell populations may be provided for only a subset of the logic levels. The read points for translating the threshold voltages are derived for all of the logic levels based upon this subset.
    Type: Application
    Filed: October 23, 2003
    Publication date: June 3, 2004
    Inventors: Shahzad B. Khalid, Daniel C. Guterman, Geoffrey S. Gongwer, Richard Simko, Kevin M. Conley
  • Patent number: 6714449
    Abstract: The present invention presents several techniques for using writable tracking cells. Multiple tracking cells are provided for each write block of the memory. These cells are re-programmed each time the user cells of the associated write block are written, preferably at the same time, using the same fixed, global reference levels to set the tracking and user cell programmed thresholds. The threshold voltages of the tracking cells are read every time the user cells are read, and these thresholds are used to determine the stored logic levels of the user cells. In one set of embodiments, populations of one or more tracking cells are associated with different logic levels of a multi-state memory. These tracking cell populations may be provided for only a subset of the logic levels. The read points for translating the threshold voltages are derived for all of the logic levels based upon this subset.
    Type: Grant
    Filed: January 24, 2003
    Date of Patent: March 30, 2004
    Assignee: SanDisk Corporation
    Inventor: Shahzad B. Khalid
  • Patent number: 6678192
    Abstract: A memory system (e.g., memory card) having error management for stored levels (e.g., reference levels) used in discrimination of logic levels for data storage units providing data storage is disclosed. The stored levels can be stored in predetermined storage units (e.g., writable tracking storage units) in the memory system. The memory system is typically a non-volatile memory product or device that provides binary or multi-state data storage.
    Type: Grant
    Filed: November 2, 2001
    Date of Patent: January 13, 2004
    Assignee: SanDisk Corporation
    Inventors: Geoffrey S. Gongwer, Shahzad B. Khalid, Daniel C. Guterman
  • Publication number: 20030112692
    Abstract: A memory system (e.g., memory card) offering hybrid density storage is disclosed. The memory system yields both high density storage and high performance operation. According to one aspect, certain data to be stored in the memory system can be stored in lower density storage so that it provides robust storage and/or high speed retrieval. Other data, which can be retrieved at moderate speeds or moderate robustness, can be stored to higher density storage in a space (area) efficient manner.
    Type: Application
    Filed: December 14, 2001
    Publication date: June 19, 2003
    Applicant: SanDisk Corporation
    Inventors: Carlos Gonzalez, Shahzad B. Khalid
  • Publication number: 20030112661
    Abstract: The present invention presents several techniques for using writable tracking cells. Multiple tracking cells are provided for each write block of the memory. These cells are re-programmed each time the user cells of the associated write block are written, preferably at the same time, using the same fixed, global reference levels to set the tracking and user cell programmed thresholds. The threshold voltages of the tracking cells are read every time the user cells are read, and these thresholds are used to determine the stored logic levels of the user cells. In one set of embodiments, populations of one or more tracking cells are associated with different logic levels of a multi-state memory. These tracking cell populations may be provided for only a subset of the logic levels. The read points for translating the threshold voltages are derived for all of the logic levels based upon this subset.
    Type: Application
    Filed: January 24, 2003
    Publication date: June 19, 2003
    Inventors: Shahzad B. Khalid, Daniel C. Guterman, Geoffrey S. Gongwer, Richard Simko, Kevin M. Conley
  • Publication number: 20030086293
    Abstract: A memory system (e.g., memory card) having error management for stored levels (e.g., reference levels) used in discrimination of logic levels for data storage units providing data storage is disclosed. The stored levels can be stored in predetermined storage units (e.g., writable tracking storage units) in the memory system. The memory system is typically a non-volatile memory product or device that provides binary or multi-state data storage.
    Type: Application
    Filed: November 2, 2001
    Publication date: May 8, 2003
    Applicant: SanDisk Corporation
    Inventors: Geoffrey S. Gongwer, Shahzad B. Khalid, Daniel C. Guterman
  • Patent number: 6538922
    Abstract: The present invention presents several techniques for using writable tracking cells. Multiple tracking cells are provided for each write block of the memory. These cells are re-programmed each time the user cells of the associated write block are written, preferably at the same time, using the same fixed, global reference levels to set the tracking and user cell programmed thresholds. The threshold voltages of the tracking cells are read every time the user cells are read, and these thresholds are used to determine the stored logic levels of the user cells. In one set of embodiments, populations of one or more tracking cells are associated with different logic levels of a multi-state memory. These tracking cell populations may be provided for only a subset of the logic levels. The read points for translating the threshold voltages are derived for all of the logic levels based upon this subset.
    Type: Grant
    Filed: September 27, 2000
    Date of Patent: March 25, 2003
    Assignee: SanDisk Corporation
    Inventors: Shahzad B. Khalid, Daniel C. Guterman, Geoffrey S. Gongwer, Richard Simko, Kevin M. Conley