Patents by Inventor Gautam A. Dusija

Gautam A. Dusija 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: 11626183
    Abstract: A storage system has a memory with a multi-level cell (MLC) block and a partially-bad single-level cell (SLC) block. The storage system repurposes the partially-bad SLC block as a non-volatile read cache for data stored in the MLC block (e.g., cold data that is read relatively frequently) to improve performance of host reads. Because the original version of the data is still stored in the MLC block, the original version of the data can be read if there is an error in the copy of the data stored in the partially-bad SLC block, thus avoiding the need for extensive error-correction handling to account for the poor reliability of the partially-bad SLC block.
    Type: Grant
    Filed: August 9, 2021
    Date of Patent: April 11, 2023
    Assignee: Western Digital Technologies, Inc.
    Inventors: Kalpit Bordia, Gautam Dusija
  • Publication number: 20230045156
    Abstract: A storage system has a memory with a multi-level cell (MLC) block and a partially-bad single-level cell (SLC) block. The storage system repurposes the partially-bad SLC block as a non-volatile read cache for data stored in the MLC block (e.g., cold data that is read relatively frequently) to improve performance of host reads. Because the original version of the data is still stored in the MLC block, the original version of the data can be read if there is an error in the copy of the data stored in the partially-bad SLC block, thus avoiding the need for extensive error-correction handling to account for the poor reliability of the partially-bad SLC block.
    Type: Application
    Filed: August 9, 2021
    Publication date: February 9, 2023
    Applicant: Western Digital Technologies, Inc.
    Inventors: Kalpit Bordia, Gautam Dusija
  • Patent number: 10998073
    Abstract: Disclosed is an apparatus including a memory device. The memory device includes a memory array, a number of non-volatile memory sections configured to store a copy of operational information for the memory array, and a controller coupled to the number of non-volatile memory sections. The controller can responsive to a first wake-up operation, select a first non-volatile memory section as a starting section to retrieve the copy of operational information. The controller can responsive to a second wake-up operation, select a second non-volatile memory section as the starting section to retrieve the copy of operational information without regard to success of a prior attempt to retrieve the copy of operational information.
    Type: Grant
    Filed: February 28, 2019
    Date of Patent: May 4, 2021
    Assignee: Western Digital Technologies, Inc.
    Inventors: Phil Reusswig, Sahil Sharma, Gautam Dusija
  • Patent number: 10936415
    Abstract: An error correction scheme in flash memory. Methods include extending a lifetime of a memory block, including: receiving an indication that an error occurred during a write operation at a first location in a memory block, the first location associated with a faulty page of the memory block; and performing a modified exclusive OR (XOR) scheme on the memory block by: performing a de-XOR operation that generates recovery data of the faulty page; storing the recovery data in a location different from the faulty page of memory; marking the faulty page for exclusion in future de-XOR operations; and performing a parity calculation that generates an updated parity value that includes all pages of the memory block that have been programmed except for the faulty page.
    Type: Grant
    Filed: June 28, 2019
    Date of Patent: March 2, 2021
    Assignee: Western Digital Technologies, Inc.
    Inventors: Chris Yip, Piyush Sagdeo, Gautam Dusija, Vidhu Gupta
  • Publication number: 20200409787
    Abstract: An error correction scheme in flash memory. Methods include extending a lifetime of a memory block, including: receiving an indication that an error occurred during a write operation at a first location in a memory block, the first location associated with a faulty page of the memory block; and performing a modified exclusive OR (XOR) scheme on the memory block by: performing a de-XOR operation that generates recovery data of the faulty page; storing the recovery data in a location different from the faulty page of memory; marking the faulty page for exclusion in future de-XOR operations; and performing a parity calculation that generates an updated parity value that includes all pages of the memory block that have been programmed except for the faulty page.
    Type: Application
    Filed: June 28, 2019
    Publication date: December 31, 2020
    Applicant: Western Digital Technologies, Inc.
    Inventors: Chris Yip, Piyush Sagdeo, Gautam Dusija, Vidhu Gupta
  • Publication number: 20200279611
    Abstract: Disclosed is an apparatus including a memory device. The memory device includes a memory array, a number of non-volatile memory sections configured to store a copy of operational information for the memory array, and a controller coupled to the number of non-volatile memory sections. The controller can responsive to a first wake-up operation, select a first non-volatile memory section as a starting section to retrieve the copy of operational information. The controller can responsive to a second wake-up operation, select a second non-volatile memory section as the starting section to retrieve the copy of operational information without regard to success of a prior attempt to retrieve the copy of operational information.
    Type: Application
    Filed: February 28, 2019
    Publication date: September 3, 2020
    Applicant: Western Digital Technologies, Inc.
    Inventors: Phil Reusswig, Sahil Sharma, Gautam Dusija
  • Patent number: 10635585
    Abstract: In an on-chip copy process, performed by a storage device, data is copied from a plurality of Single Level Cell (SLC) blocks of non-volatile three-dimensional memory (e.g., 3D flash memory) in a respective memory die to a Multilevel Cell (MLC) block of the same memory die. A copy of source data from a respective SLC block is interleaved with a copy of source data from one or more other SLC blocks in the memory die to produce interleaved source data. Each source data copy that is interleaved is rotated by an offset assigned to the respective SLC block from which the source data is copied, and each respective SLC block in the plurality of SLC blocks is assigned a distinct offset. Each distinct set of the interleaved source data is written to a distinct respective MLC page of the MLC block.
    Type: Grant
    Filed: June 15, 2018
    Date of Patent: April 28, 2020
    Assignee: Western Digital Technologies, Inc.
    Inventors: Abhilash R. Kashyap, Gautam A. Dusija, Deepak Raghu, Chris Nga Yee Yip
  • Publication number: 20190354478
    Abstract: In an on-chip copy process, performed by a storage device, data is copied from a plurality of Single Level Cell (SLC) blocks of non-volatile three-dimensional memory (e.g., 3D flash memory) in a respective memory die to a Multilevel Cell (MLC) block of the same memory die. A copy of source data from a respective SLC block is interleaved with a copy of source data from one or more other SLC blocks in the memory die to produce interleaved source data. Each source data copy that is interleaved is rotated by an offset assigned to the respective SLC block from which the source data is copied, and each respective SLC block in the plurality of SLC blocks is assigned a distinct offset. Each distinct set of the interleaved source data is written to a distinct respective MLC page of the MLC block.
    Type: Application
    Filed: June 15, 2018
    Publication date: November 21, 2019
    Inventors: Abhilash R. Kashyap, Gautam A. Dusija, Deepak Raghu, Chris Nga Yee Yip
  • Patent number: 9978456
    Abstract: Techniques are presented to reduce the amount of read disturb on partially written blocks of NAND type non-volatile memory, both for when determining the last written word line in a block and also for data read. In both cases, non-selected word lines that are unwritten or, in the case of finding the last written word line, may be unwritten are biased with a lower read-pass voltage then is typically used. The result of such reads can also be applied to an algorithm for finding the last written word by skipping a varying number of word lines. Performance in a last written page determination can also be improved by use of shorter bit line settling times than for a standard read.
    Type: Grant
    Filed: November 17, 2014
    Date of Patent: May 22, 2018
    Assignee: SanDisk Technologies LLC
    Inventors: Anubhav Khandelwal, Dana Lee, Abhijeet Manohar, Henry Chin, Gautam Dusija, Daniel Tuers, Chris Avila, Cynthia Hsu
  • Patent number: 9785357
    Abstract: Systems and methods for sampling data at a non-volatile memory system are disclosed. In one implementation, a controller of a non-volatile memory system that is coupled with a host device acquires a read level voltage of a first word line of a memory block of a non-volatile memory of the non-volatile memory system. The controller accesses one or more lookup tables to determine an offset voltage for a second word line of the memory block based on a program/erase count and a read/disturb count associated with the memory block; applies the read level voltage and the offset voltage to the second word line to sample data stored at the memory block; and determines whether the data sampled from the memory block contains errors.
    Type: Grant
    Filed: October 20, 2015
    Date of Patent: October 10, 2017
    Assignee: SANDISK TECHNOLOGIES LLC
    Inventors: Deepak Raghu, Chris Aviala, Harish Singidi, Guirong Liang, Anne Pao-Ling Koh, Dana Lee, Gautam Dusija
  • Patent number: 9741444
    Abstract: Methods and systems are provided where non-volatile solid state memory may include selected memory cells coupled to a selected word line and proxy memory cells coupled to a proxy word line. The selected memory cells may be non-adjacent to the proxy memory cells and be selected for a read operation. A read proxy voltage may be applied to the proxy word line when data is read from the selected memory cells. A read disturb may be determined based on a difference between a predetermined value stored in the proxy memory cells and a value read from the proxy memory cells.
    Type: Grant
    Filed: April 10, 2017
    Date of Patent: August 22, 2017
    Assignee: SanDisk Technologies LLC
    Inventors: Philip Reusswig, Harish Singidi, Deepak Raghu, Gautam Dusija, Pao-Ling Koh, Chris Avila
  • Publication number: 20170213599
    Abstract: Methods and systems are provided where non-volatile solid state memory may include selected memory cells coupled to a selected word line and proxy memory cells coupled to a proxy word line. The selected memory cells may be non-adjacent to the proxy memory cells and be selected for a read operation. A read proxy voltage may be applied to the proxy word line when data is read from the selected memory cells. A read disturb may be determined based on a difference between a predetermined value stored in the proxy memory cells and a value read from the proxy memory cells.
    Type: Application
    Filed: April 10, 2017
    Publication date: July 27, 2017
    Inventors: Philip Reusswig, Harish Singidi, Deepak Raghu, Gautam Dusija, Pao-Ling Koh, Chris Avila
  • Patent number: 9646709
    Abstract: Methods and systems are provided where non-volatile solid state memory may include selected memory cells coupled to a selected word line and proxy memory cells coupled to a proxy word line. The selected memory cells may be non-adjacent to the proxy memory cells and be selected for a read operation. A read proxy voltage may be applied to the proxy word line when data is read from the selected memory cells. A read disturb may be determined based on a difference between a predetermined value stored in the proxy memory cells and a value read from the proxy memory cells.
    Type: Grant
    Filed: September 11, 2015
    Date of Patent: May 9, 2017
    Assignee: SanDisk Technologies, LLC
    Inventors: Philip Reusswig, Harish Singidi, Deepak Raghu, Gautam Dusija, Pao-Ling Koh, Chris Avila
  • Publication number: 20170109040
    Abstract: Systems and methods for sampling data at a non-volatile memory system are disclosed. In one implementation, a controller of a non-volatile memory system that is coupled with a host device acquires a read level voltage of a first word line of a memory block of a non-volatile memory of the non-volatile memory system. The controller accesses one or more lookup tables to determine an offset voltage for a second word line of the memory block based on a program/erase count and a read/disturb count associated with the memory block; applies the read level voltage and the offset voltage to the second word line to sample data stored at the memory block; and determines whether the data sampled from the memory block contains errors.
    Type: Application
    Filed: October 20, 2015
    Publication date: April 20, 2017
    Applicant: SANDISK TECHNOLOGIES INC.
    Inventors: Deepak Raghu, Chris Aviala, Harish Singidi, Guirong Liang, Anne Pao-LIng Koh, Dana Lee, Gautam Dusija
  • Patent number: 9626289
    Abstract: Systems and methods for metablock relinking may be provided. A first physical block of a first metablock may be determined to have a different health than a second physical block of a second metablock based on health indicators of the first and second physical blocks. Each of the health indicators may indicate an extent to which a respective one of the first and second physical blocks may be written to and/or erased before the respective one of the first and second physical blocks becomes defective. The first physical block of the first metablock may be replaced with the second physical block of the second metablock based on a determination that the health of the first physical block of the first metablock is different than the health of the second physical block of the second metablock.
    Type: Grant
    Filed: August 28, 2014
    Date of Patent: April 18, 2017
    Assignee: SanDisk Technologies LLC
    Inventors: Lei Chen, Xinde Hu, Zhenlei Shen, Yiwei Song, Gautam Dusija
  • Publication number: 20170076811
    Abstract: Methods and systems are provided where non-volatile solid state memory may include selected memory cells coupled to a selected word line and proxy memory cells coupled to a proxy word line. The selected memory cells may be non-adjacent to the proxy memory cells and be selected for a read operation. A read proxy voltage may be applied to the proxy word line when data is read from the selected memory cells. A read disturb may be determined based on a difference between a predetermined value stored in the proxy memory cells and a value read from the proxy memory cells.
    Type: Application
    Filed: September 11, 2015
    Publication date: March 16, 2017
    Inventors: Philip Reusswig, Harish Singidi, Deepak Raghu, Gautam Dusija, Pao-Ling Koh, Chris Avila
  • Patent number: 9589645
    Abstract: Systems, apparatuses, and methods may be provided that adapt to trim set advancement. Trim set advancement may be a change in trim sets over time. A cell of a semiconductor memory may have a first charge level and be programmed with a first trim set. The cell may be reprogrammed by raising the first charge level to a second charge level that corresponds to the cell programmed with a second trim set.
    Type: Grant
    Filed: October 6, 2014
    Date of Patent: March 7, 2017
    Assignee: SanDisk Technologies LLC
    Inventors: Gautam Dusija, Chris Avila, Jonathan Hsu, Neil Darragh, Bo Lei
  • Patent number: 9484098
    Abstract: A population of memory cells are programmed and an indicator of a first number of the memory cells programmed to a first state is recorded. Subsequently, a first read operation is performed using a first set of read parameters to identify a second number of the memory cells that are read as being in the first state. The difference between the first number and the second number is determined and a second set of read parameters for a second read (reread) is selected accordingly.
    Type: Grant
    Filed: August 5, 2015
    Date of Patent: November 1, 2016
    Assignee: SanDisk Technologies LLC
    Inventors: Jonathan Hsu, Gautam Dusija
  • Publication number: 20160180945
    Abstract: A method of searching for a boundary between a written portion and an unwritten portion of an open block may include performing a word line by word line binary search of a first physical area of the open block to identify a last written word line of the first physical area of the block, and subsequently, searching in at least a second physical area of the open block based on the last written word line of the first physical area of the block as identified by the binary search.
    Type: Application
    Filed: December 23, 2014
    Publication date: June 23, 2016
    Inventors: Yew Yin Ng, Gautam Dusija, Dennis Ea, Mrinal Kochar
  • Patent number: 9361991
    Abstract: A method of searching for a boundary between a written portion and an unwritten portion of an open block may include performing a word line by word line binary search of a first physical area of the open block to identify a last written word line of the first physical area of the block, and subsequently, searching in at least a second physical area of the open block based on the last written word line of the first physical area of the block as identified by the binary search.
    Type: Grant
    Filed: December 23, 2014
    Date of Patent: June 7, 2016
    Assignee: SanDisk Technologies Inc.
    Inventors: Yew Yin Ng, Gautam Dusija, Dennis S. Ea, Mrinal Kochar