Patents by Inventor Shahzad Khalid

Shahzad 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: 8873303
    Abstract: A non-volatile memory device capable of reading and writing a large number of memory cells with multiple read/write circuits in parallel has an architecture that reduces redundancy in the multiple read/write circuits to a minimum. The multiple read/write circuits are organized into a bank of similar stacks of components. Redundant circuits such as a processor for processing data among stacks each associated with multiple memory cells are factored out. The processor is implemented with an input logic, a latch and an output logic. The input logic can transform the data received from either the sense amplifier or the data latches. The output logic further processes the transformed data to send to either the sense amplifier or the data latches or to a controller. This provides an infrastructure with maximum versatility and a minimum of components for sophisticated processing of the data sensed and the data to be input or output.
    Type: Grant
    Filed: October 7, 2010
    Date of Patent: October 28, 2014
    Assignee: Sandisk Technologies, Inc.
    Inventors: Raul-Adrian Cernea, Yan Li, Shahzad Khalid, Siu Lung Chan
  • Patent number: 8072817
    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. Read operations are performed on the tracking cells, where threshold voltages of physical states of the tracking cells are further apart than threshold voltages of physical states of non-tracking cells. Based on the read operations, an extent to which the tracking cells are errored is determined.
    Type: Grant
    Filed: February 18, 2011
    Date of Patent: December 6, 2011
    Assignee: SanDisk Technologies Inc.
    Inventors: Daniel C Guterman, Stephen J Gross, Shahzad Khalid, Geoffrey S Gongwer
  • Publication number: 20110141816
    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. Read operations are performed on the tracking cells, where threshold voltages of physical states of the tracking cells are further apart than threshold voltages of physical states of non-tracking cells. Based on the read operations, an extent to which the tracking cells are errored is determined.
    Type: Application
    Filed: February 18, 2011
    Publication date: June 16, 2011
    Applicant: SANDISK CORPORATION
    Inventors: Daniel C. Guterman, Stephen J. Gross, Shahzad Khalid, Geoffrey S. Gongwer
  • Publication number: 20110019485
    Abstract: A non-volatile memory device capable of reading and writing a large number of memory cells with multiple read/write circuits in parallel has an architecture that reduces redundancy in the multiple read/write circuits to a minimum. The multiple read/write circuits are organized into a bank of similar stacks of components. Redundant circuits such as a processor for processing data among stacks each associated with multiple memory cells are factored out. The processor is implemented with an input logic, a latch and an output logic. The input logic can transform the data received from either the sense amplifier or the data latches. The output logic further processes the transformed data to send to either the sense amplifier or the data latches or to a controller. This provides an infrastructure with maximum versatility and a minimum of components for sophisticated processing of the data sensed and the data to be input or output.
    Type: Application
    Filed: October 7, 2010
    Publication date: January 27, 2011
    Inventors: Raul-Adrian Cernea, Yan Li, Shahzad Khalid, Siu Lung Chan
  • Patent number: 7817476
    Abstract: A non-volatile memory device capable of reading and writing a large number of memory cells with multiple read/write circuits in parallel has an architecture that reduces redundancy in the multiple read/write circuits to a minimum. The multiple read/write circuits are organized into a bank of similar stacks of components. Redundant circuits such as a processor for processing data among stacks each associated with multiple memory cells are factored out. The processor is implemented with an input logic, a latch and an output logic. The input logic can transform the data received from either the sense amplifier or the data latches. The output logic further processes the transformed data to send to either the sense amplifier or the data latches or to a controller. This provides an infrastructure with maximum versatility and a minimum of components for sophisticated processing of the data sensed and the data to be input or output.
    Type: Grant
    Filed: December 23, 2008
    Date of Patent: October 19, 2010
    Assignee: Sandisk Corporation
    Inventors: Raul-Adrian Cernea, Yan Li, Shahzad Khalid, Siu Lung Chan
  • Patent number: 7760555
    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.
    Type: Grant
    Filed: May 22, 2007
    Date of Patent: July 20, 2010
    Assignee: Sandisk Corporation
    Inventors: Daniel C. Guterman, Stephen J. Gross, Shahzad Khalid, Geoffrey S. Gongwer
  • Patent number: 7681094
    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.
    Type: Grant
    Filed: May 22, 2007
    Date of Patent: March 16, 2010
    Assignee: Sandisk Corporation
    Inventors: Daniel C. Guterman, Stephen J. Gross, Shahzad Khalid, Geoffrey S. Gongwer
  • Patent number: 7539060
    Abstract: A non-volatile storage device in which current sensing is performed for a non-volatile storage element. A voltage is applied to a selected word line of the first non-volatile storage element, and source and p-well voltages are applied to a source and a p-well, respectively, associated with the non-volatile storage element. The source and p-well voltages are regulated at respective positive DC levels to avoid a ground bounce, or voltage fluctuation, which would occur if the source voltage at least was regulated at a ground voltage. A programming condition of the non-volatile storage element is determined by sensing a current in a NAND string of the non-volatile storage element. The sensing can occur quickly since there is no delay in waiting for the ground bounce to settle.
    Type: Grant
    Filed: June 29, 2007
    Date of Patent: May 26, 2009
    Assignee: SanDisk Corporation
    Inventors: Hao Thai Nguyen, Seungpil Lee, Man Lung Mui, Shahzad Khalid, Hock So, Prashanti Govindu
  • Patent number: 7532516
    Abstract: A non-volatile storage device in which current sensing is performed for a non-volatile storage element with a negative threshold voltage. A control gate read voltage is applied to a selected word line of a non-volatile storage element, and source and p-well voltages are applied to a source and a p-well, respectively, associated with the non-volatile storage element. The source and p-well voltages exceed the control gate read voltage so that a positive control gate read voltage can be used. There is no need for a negative charge pump to apply a negative word line voltage even for sensing a negative threshold voltage. A programming condition of the non-volatile storage element is determined by sensing a voltage drop which is tied to a fixed current which flows in a NAND string of the non-volatile storage element.
    Type: Grant
    Filed: June 29, 2007
    Date of Patent: May 12, 2009
    Assignee: SanDisk Corporation
    Inventors: Hao Thai Nguyen, Seungpil Lee, Man Lung Mui, Shahzad Khalid, Hock So, Prashanti Govindu, Nima Mokhlesi, Deepak Chandra Sekar
  • Patent number: 7532514
    Abstract: When programming a contiguous page of memory storage units, every time a memory storage unit has reached its targeted state and is program-inhibited or locked out from further programming, it creates a perturbation on an adjacent memory storage unit still under programming. The present invention provides as part of a programming circuit and method in which an offset to the perturbation is added to the adjacent memory storage unit still under programming. The offset is added by a controlled coupling between the adjacent bit lines of the program-inhibited memory storage unit and the still under programming memory storage unit. In this way, an error inherent in programming in parallel high-density memory storage units is eliminated or minimized.
    Type: Grant
    Filed: August 31, 2007
    Date of Patent: May 12, 2009
    Assignee: Sandisk Corporation
    Inventors: Raul-Adrian Cernea, Yan Li, Mehrdad Mofidi, Shahzad Khalid
  • Publication number: 20090103369
    Abstract: A non-volatile memory device capable of reading and writing a large number of memory cells with multiple read/write circuits in parallel has an architecture that reduces redundancy in the multiple read/write circuits to a minimum. The multiple read/write circuits are organized into a bank of similar stacks of components. Redundant circuits such as a processor for processing data among stacks each associated with multiple memory cells are factored out. The processor is implemented with an input logic, a latch and an output logic. The input logic can transform the data received from either the sense amplifier or the data latches. The output logic further processes the transformed data to send to either the sense amplifier or the data latches or to a controller. This provides an infrastructure with maximum versatility and a minimum of components for sophisticated processing of the data sensed and the data to be input or output.
    Type: Application
    Filed: December 23, 2008
    Publication date: April 23, 2009
    Inventors: Raul-Adrian Cernea, Yan Li, Shahzad Khalid, Siu Lung Chan
  • Patent number: 7489554
    Abstract: Current sensing is performed in a non-volatile storage device for a non-volatile storage element. A voltage is applied to a selected word line of the first non-volatile storage element, and source and p-well voltages are applied to a source and a p-well, respectively, associated with the non-volatile storage element. The source and p-well voltages are regulated at respective positive DC levels to avoid a ground bounce, or voltage fluctuation, which would occur if the source voltage at least was regulated at a ground voltage. A programming condition of the non-volatile storage element is determined by sensing a current in a NAND string of the non-volatile storage element. The sensing can occur quickly since there is no delay in waiting for the ground bounce to settle.
    Type: Grant
    Filed: June 29, 2007
    Date of Patent: February 10, 2009
    Assignee: SanDisk Corporation
    Inventors: Hao Thai Nguyen, Seungpil Lee, Man Lung Mui, Shahzad Khalid, Hock So, Prashanti Govindu
  • Patent number: 7471575
    Abstract: A non-volatile memory device capable of reading and writing a large number of memory cells with multiple read/write circuits in parallel has an architecture that reduces redundancy in the multiple read/write circuits to a minimum. The multiple read/write circuits are organized into a bank of similar stacks of components. Redundant circuits such as a processor for processing data among stacks each associated with multiple memory cells are factored out. The processor is implemented with an input logic, a latch and an output logic. The input logic can transform the data received from either the sense amplifier or the data latches. The output logic further processes the transformed data to send to either the sense amplifier or the data latches or to a controller. This provides an infrastructure with maximum versatility and a minimum of components for sophisticated processing of the data sensed and the data to be input or output.
    Type: Grant
    Filed: July 23, 2007
    Date of Patent: December 30, 2008
    Assignee: Sandisk Corporation
    Inventors: Raul-Adrian Cernea, Yan Li, Shahzad Khalid, Siu Lung Chan
  • Patent number: 7471139
    Abstract: A voltage buffer for capacitive loads isolates the load from the feedback loop. Using a variation of a follower arrangement, a second transistor outside of the feedback loop introduced. The current to the load is supplied through the second transistor, which is connected to have the same control gate level as the transistor in the feedback loop and provide an output voltage based on the reference input voltage. The output voltage is dependent upon the input voltage, but the load is removed from the feedback loop. By removing the load from the feedback loop, the loop is stabilized with only a very small or no compensating capacitor, allowing the quiescent current of the buffer to be reduced and the settling time to be improved. One preferred use of the present invention is to drive the data storage elements of a non-volatile memory.
    Type: Grant
    Filed: January 4, 2007
    Date of Patent: December 30, 2008
    Assignee: SanDisk Corporation
    Inventor: Shahzad Khalid
  • Patent number: 7447079
    Abstract: Current sensing is performed in a non-volatile storage device for a selected non-volatile storage element with a negative threshold voltage. A control gate read voltage is applied to a selected word line of a non-volatile storage element, and source and p-well voltages are applied to a source and a p-well, respectively, associated with the non-volatile storage element. The source and p-well voltages exceed the control gate read voltage so that a positive control gate read voltage can be used. There is no need for a negative charge pump to apply a negative word line voltage even for sensing a negative threshold voltage. A programming condition of the non-volatile storage element is determined by sensing a voltage drop which is tied to a fixed current which flows in a NAND string of the non-volatile storage element.
    Type: Grant
    Filed: June 29, 2007
    Date of Patent: November 4, 2008
    Assignee: SanDisk Corporation
    Inventors: Hao Thai Nguyen, Seungpil Lee, Man Lung Mui, Shahzad Khalid, Hock So, Prashanti Govindu, Nima Mokhlesi, Deepak Chandra Sekar
  • Publication number: 20080247229
    Abstract: A non-volatile storage device in which current sensing is performed for a non-volatile storage element. A voltage is applied to a selected word line of the first non-volatile storage element, and source and p-well voltages are applied to a source and a p-well, respectively, associated with the non-volatile storage element. The source and p-well voltages are regulated at respective positive DC levels to avoid a ground bounce, or voltage fluctuation, which would occur if the source voltage at least was regulated at a ground voltage. A programming condition of the non-volatile storage element is determined by sensing a current in a NAND string of the non-volatile storage element. The sensing can occur quickly since there is no delay in waiting for the ground bounce to settle.
    Type: Application
    Filed: June 29, 2007
    Publication date: October 9, 2008
    Inventors: Hao Thai Nguyen, Seungpil Lee, Man Lung Mui, Shahzad Khalid, Hock So, Prashanti Govindu
  • Publication number: 20080247228
    Abstract: A non-volatile storage device in which current sensing is performed for a non-volatile storage element with a negative threshold voltage. A control gate read voltage is applied to a selected word line of a non-volatile storage element, and source and p-well voltages are applied to a source and a p-well, respectively, associated with the non-volatile storage element. The source and p-well voltages exceed the control gate read voltage so that a positive control gate read voltage can be used. There is no need for a negative charge pump to apply a negative word line voltage even for sensing a negative threshold voltage. A programming condition of the non-volatile storage element is determined by sensing a voltage drop which is tied to a fixed current which flows in a NAND string of the non-volatile storage element.
    Type: Application
    Filed: June 29, 2007
    Publication date: October 9, 2008
    Inventors: Hao Thai Nguyen, Seungpil Lee, Man Lung Mui, Shahzad Khalid, Hock So, Prashanti Govindu, Nima Mokhlesi, Deepak Chandra Sekar
  • Publication number: 20080247238
    Abstract: Current sensing is performed in a non-volatile storage device for a selected non-volatile storage element with a negative threshold voltage. A control gate read voltage is applied to a selected word line of a non-volatile storage element, and source and p-well voltages are applied to a source and a p-well, respectively, associated with the non-volatile storage element. The source and p-well voltages exceed the control gate read voltage so that a positive control gate read voltage can be used. There is no need for a negative charge pump to apply a negative word line voltage even for sensing a negative threshold voltage. A programming condition of the non-volatile storage element is determined by sensing a voltage drop which is tied to a fixed current which flows in a NAND string of the non-volatile storage element.
    Type: Application
    Filed: June 29, 2007
    Publication date: October 9, 2008
    Inventors: Hao Thai Nguyen, Seungpil Lee, Man Lung Mui, Shahzad Khalid, Hock So, Prashanti Govindu, Nima Mokhlesi, Deepak Chandra Sekar
  • Publication number: 20080247239
    Abstract: Current sensing is performed in a non-volatile storage device for a non-volatile storage element. A voltage is applied to a selected word line of the first non-volatile storage element, and source and p-well voltages are applied to a source and a p-well, respectively, associated with the non-volatile storage element. The source and p-well voltages are regulated at respective positive DC levels to avoid a ground bounce, or voltage fluctuation, which would occur if the source voltage at least was regulated at a ground voltage. A programming condition of the non-volatile storage element is determined by sensing a current in a NAND string of the non-volatile storage element. The sensing can occur quickly since there is no delay in waiting for the ground bounce to settle.
    Type: Application
    Filed: June 29, 2007
    Publication date: October 9, 2008
    Inventors: Hao Thai Nguyen, Seungpil Lee, Man Lung Mui, Shahzad Khalid, Hock So, Prashanti Govindu
  • Publication number: 20070297234
    Abstract: When programming a contiguous page of memory storage units, every time a memory storage unit has reached its targeted state and is program-inhibited or locked out from further programming, it creates a perturbation on an adjacent memory storage unit still under programming. The present invention provides as part of a programming circuit and method in which an offset to the perturbation is added to the adjacent memory storage unit still under programming. The offset is added by a controlled coupling between the adjacent bit lines of the program-inhibited memory storage unit and the still under programming memory storage unit. In this way, an error inherent in programming in parallel high-density memory storage units is eliminated or minimized.
    Type: Application
    Filed: August 31, 2007
    Publication date: December 27, 2007
    Inventors: Raul-Adrian Cernea, Yan Li, Mehrdad Mofidi, Shahzad Khalid