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).
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Patent number: 7301807Abstract: 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: GrantFiled: February 22, 2005Date of Patent: November 27, 2007Assignee: SanDisk CorporationInventors: Shahzad B. Khalid, Daniel C. Guterman, Geoffrey S. Gongwer, Richard Simko, Kevin M. Conley
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Patent number: 6873549Abstract: 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: GrantFiled: October 23, 2003Date of Patent: March 29, 2005Assignee: SanDisk CorporationInventors: Shahzad B. Khalid, Daniel C. Guterman, Geoffrey S. Gongwer, Richard Simko, Kevin M. Conley
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Patent number: 6807106Abstract: 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: GrantFiled: December 14, 2001Date of Patent: October 19, 2004Assignee: SanDisk CorporationInventors: Carlos Gonzales, Shahzad B. Khalid
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Publication number: 20040105307Abstract: 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: ApplicationFiled: October 23, 2003Publication date: June 3, 2004Inventors: Shahzad B. Khalid, Daniel C. Guterman, Geoffrey S. Gongwer, Richard Simko, Kevin M. Conley
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Patent number: 6714449Abstract: 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: GrantFiled: January 24, 2003Date of Patent: March 30, 2004Assignee: SanDisk CorporationInventor: Shahzad B. Khalid
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Patent number: 6678192Abstract: 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: GrantFiled: November 2, 2001Date of Patent: January 13, 2004Assignee: SanDisk CorporationInventors: Geoffrey S. Gongwer, Shahzad B. Khalid, Daniel C. Guterman
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Publication number: 20030112692Abstract: 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: ApplicationFiled: December 14, 2001Publication date: June 19, 2003Applicant: SanDisk CorporationInventors: Carlos Gonzalez, Shahzad B. Khalid
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Publication number: 20030112661Abstract: 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: ApplicationFiled: January 24, 2003Publication date: June 19, 2003Inventors: Shahzad B. Khalid, Daniel C. Guterman, Geoffrey S. Gongwer, Richard Simko, Kevin M. Conley
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Publication number: 20030086293Abstract: 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: ApplicationFiled: November 2, 2001Publication date: May 8, 2003Applicant: SanDisk CorporationInventors: Geoffrey S. Gongwer, Shahzad B. Khalid, Daniel C. Guterman
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Patent number: 6538922Abstract: 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: GrantFiled: September 27, 2000Date of Patent: March 25, 2003Assignee: SanDisk CorporationInventors: Shahzad B. Khalid, Daniel C. Guterman, Geoffrey S. Gongwer, Richard Simko, Kevin M. Conley