Patents by Inventor Shashi Kiran CHILAPPAGARI

Shashi Kiran CHILAPPAGARI 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: 9385753
    Abstract: Systems and methods are provided for decoding data. A decoder receives a variable node value and reliability data for a variable node, and check node values for check nodes associated with the variable node. Circuitry generates an updated variable node value, based on the received reliability data and the received check node values. The circuitry also generates, for at least one check node, an updated check node value based on the updated variable node value.
    Type: Grant
    Filed: February 4, 2014
    Date of Patent: July 5, 2016
    Assignee: Marvell World Trade Ltd.
    Inventors: Nedeljko Varnica, Dung Viet Nguyen, Shashi Kiran Chilappagari
  • Patent number: 9379738
    Abstract: Systems and methods are provided for decoding data. A decoder receives a plurality of variable node values for a plurality of variable nodes and processed reliability data for at least a subset of the plurality of variable nodes. Circuitry updates the variable node values based on the variable node values and the processed reliability data. The processed reliability data represents a version of the reliability data for at least the subset of the plurality of variable nodes.
    Type: Grant
    Filed: March 11, 2014
    Date of Patent: June 28, 2016
    Assignee: Marvell World Trade Ltd.
    Inventors: Phong Sy Nguyen, Shashi Kiran Chilappagari, Dung Viet Nguyen
  • Patent number: 9369152
    Abstract: Systems and methods are provided for decoding data. A variable node value for a variable node is received at a first time, and reliability data for the variable node is received at a second time. The variable node is decoded using a first decoding scheme after the first time and before the second time, and the variable node is decoded using a second decoding scheme different from the first decoding scheme after the second time.
    Type: Grant
    Filed: March 5, 2014
    Date of Patent: June 14, 2016
    Assignee: Marvell World Trade Ltd.
    Inventors: Dung Viet Nguyen, Shashi Kiran Chilappagari, Phong Sy Nguyen
  • Patent number: 9323611
    Abstract: Systems and methods are provided for decoding data. A first decoder attempts to decode the data based on a hard decision input for a symbol. When the attempt to decode the data based on the hard decision input fails, a request is transmitted reliability information for the symbol. Receiving circuitry receives the reliability information for the symbol, and a second decoder decodes the data based on the reliability information.
    Type: Grant
    Filed: March 5, 2014
    Date of Patent: April 26, 2016
    Assignee: Marvell World Trade Ltd.
    Inventors: Shashi Kiran Chilappagari, Gregory Burd
  • Patent number: 9203432
    Abstract: Systems and methods are provided for decoding data. A decoder retrieves data related to a symbol and identifies a plurality of candidate values for the symbol. The decoder determines a distance between each of the plurality of candidate values and a reference value associated with the symbol to obtain a plurality of distances, and the decoder determines whether to update a value of the symbol based at least in part on the plurality of distances.
    Type: Grant
    Filed: August 23, 2013
    Date of Patent: December 1, 2015
    Assignee: Marvell World Trade Ltd.
    Inventors: Nedeljko Varnica, Shashi Kiran Chilappagari
  • Patent number: 9183942
    Abstract: A read module reads memory cells along a first word line by applying a plurality of threshold voltages to the first word line; generates first information about a first memory cell located along the first word line and a first bit line indicating a location of a threshold voltage distribution of the first memory cell relative to the plurality of threshold voltages; reads a second memory cell located along the first word line, a second word line near the first word line, or a second bit line near the first bit line; and generates second information about the second memory cell indicating a state of the second memory cell causing interference to the first memory cell. A compensation module compensates for the interference by assigning one or more of a log-likelihood ratio and a hard decision to the first memory cells based on the first information and the second information.
    Type: Grant
    Filed: December 15, 2014
    Date of Patent: November 10, 2015
    Assignee: Marvell World Trade LTD.
    Inventors: Shashi Kiran Chilappagari, Zhengang Chen, Gregory Burd
  • Patent number: 9153323
    Abstract: Systems and methods are provided to generate soft information related to the threshold voltage of a memory cell. A range of threshold voltages for the memory cell is divided into subregions of threshold voltage values herein referred to as bins. An output of the memory cell in response to an applied reference signal is measured. The applied reference signal includes a voltage value and position information. A single bin is identified based on the position information of the reference signal. The identified bin is split into more than one bin based on the output of the memory cell and the voltage value of the reference signal. The newly split bins and all the other bins that were not split are assigned new bin indices.
    Type: Grant
    Filed: February 11, 2014
    Date of Patent: October 6, 2015
    Assignee: Marvell World Trade Ltd.
    Inventors: Zhengang Chen, Gregory Burd, Shashi Kiran Chilappagari, Xueshi Yang
  • Patent number: 9152558
    Abstract: An apparatus includes, in at least one aspect, a memory interface configured to connect with a plurality of multi-level memory cells and a circuitry coupled with the memory interface. The plurality of multi-level memory cells include a first page and a second page. The first page is associated with bits of a first significance. The second page is associated with bits of a second significance. The circuitry is configured to map a first portion of an encoded data sector to the first page and map a second portion of the encoded data sector to the second page. The first portion excludes the second portion and the second portion excludes the first portion such that each of the first page and the second page contains different data from the encoded data sector.
    Type: Grant
    Filed: August 29, 2014
    Date of Patent: October 6, 2015
    Assignee: Marvell World Trade Ltd.
    Inventors: Shashi Kiran Chilappagari, Xueshi Yang, Gregory Burd
  • Patent number: 9153336
    Abstract: An apparatus including a memory array and control circuitry. The control circuitry is configured to, based at least on a plurality of read comparison results, determine a number of memory cells of the memory array that have threshold voltages that fall into each of a plurality of voltage ranges. The control circuitry is further configured to, based at least on the number of memory cells that have threshold voltages in each of the plurality of voltage ranges, estimate an offset amount that a center voltage between two threshold voltage distributions differs from a center reference voltage. The control circuitry is further configured to read one or more of the plurality of memory cells based at least in part on the estimated offset amount.
    Type: Grant
    Filed: November 1, 2013
    Date of Patent: October 6, 2015
    Assignee: Marvell International Ltd.
    Inventors: Xueshi Yang, Shashi Kiran Chilappagari
  • Publication number: 20150220391
    Abstract: Embodiments provide a method comprising estimating a first set of log-likelihood ratio (LLR) values for a plurality of memory cells of a memory; based on the first set of LLR values, performing a first error correcting code (ECC) decoding operation; in response to determining a failure of the first ECC decoding operation, generating, by adjusting the first set of LLR values, a second set of LLR values for the plurality of memory cells; and based on the second set of LLR values, performing a second ECC decoding operation.
    Type: Application
    Filed: April 13, 2015
    Publication date: August 6, 2015
    Inventors: Shashi Kiran Chilappagari, Gregory Burd, Zhengang Chen
  • Patent number: 9065623
    Abstract: Systems, methods, apparatus, and techniques are provided for producing encoded trellis coded modulation (TCM) data from user information. Encoding parameters are selected based on a target information rate. The encoding parameters include a first dimensionality value and a second dimensionality value. A first part of the user information is encoded based on the first dimensionality value to produce a first number of coded bits, and a second part of the user information is encoded based on the second dimensionality value to produce a second number of coded bits.
    Type: Grant
    Filed: September 30, 2011
    Date of Patent: June 23, 2015
    Assignee: MARVELL INTERNATIONAL LTD.
    Inventors: Zhengang Chen, Shashi Kiran Chilappagari, Xueshi Yang, Gregory Burd
  • Publication number: 20150103594
    Abstract: A read module reads memory cells along a first word line by applying a plurality of threshold voltages to the first word line; generates first information about a first memory cell located along the first word line and a first bit line indicating a location of a threshold voltage distribution of the first memory cell relative to the plurality of threshold voltages; reads a second memory cell located along the first word line, a second word line near the first word line, or a second bit line near the first bit line; and generates second information about the second memory cell indicating a state of the second memory cell causing interference to the first memory cell. A compensation module compensates for the interference by assigning one or more of a log-likelihood ratio and a hard decision to the first memory cells based on the first information and the second information.
    Type: Application
    Filed: December 15, 2014
    Publication date: April 16, 2015
    Inventors: Shashi Kiran Chilappagari, Zhengang Chen, Gregory Burd
  • Patent number: 9009574
    Abstract: Embodiments provide a method comprising estimating a first set of log-likelihood ratio (LLR) values for a plurality of memory cells of a memory; based on the first set of LLR values, performing a first error correcting code (ECC) decoding operation; in response to determining a failure of the first ECC decoding operation, generating, by adjusting the first set of LLR values, a second set of LLR values for the plurality of memory cells; and based on the second set of LLR values, performing a second ECC decoding operation.
    Type: Grant
    Filed: May 25, 2012
    Date of Patent: April 14, 2015
    Assignee: Marvell World Trade Ltd.
    Inventors: Shashi Kiran Chilappagari, Gregory Burd, Zhengang Chen
  • Patent number: 8984378
    Abstract: Systems and methods are provided for decoding data using hard decisions and soft information. In particular, the systems and methods described herein are directed to decoders having variable nodes and check nodes, each with multiple states. The systems and methods include receiving, at a decoder during a first iteration, values for each of a plurality of variable nodes, and determining, during a second iteration, one or more indications for each of a plurality of check nodes based on the one or more values of the variable nodes received during the first iteration. The methods further include updating, at the decoder during the second iteration, the values for each of the variable nodes based on the values of the respective variable node received during the first iteration, and the indications for each of the plurality connected check nodes during the first iteration.
    Type: Grant
    Filed: March 11, 2014
    Date of Patent: March 17, 2015
    Assignee: Marvell International Ltd.
    Inventors: Shashi Kiran Chilappagari, Nedeljko Varnica, Xueshi Yang, Gregory Burd
  • Patent number: 8943381
    Abstract: Systems and methods are provided for decoding data using hard decisions and erasures. Circuitry receives data from each of a plurality of variable nodes which correspond to bits of data being decoded. Each variable node stores one of at least three values. The circuitry determines processes the values received from the plurality of variable nodes according to a set of processing rules. The processing rules are used to determine a condition related to the values stored by the plurality of variable nodes. The circuitry stores an indication of the stored condition at a check node.
    Type: Grant
    Filed: February 14, 2014
    Date of Patent: January 27, 2015
    Assignee: Marvell International Ltd.
    Inventors: Nedeljko Varnica, Shashi Kiran Chilappagari, Gregory Burd
  • Publication number: 20140372687
    Abstract: An apparatus includes, in at least one aspect, a memory interface configured to connect with a plurality of multi-level memory cells and a circuitry coupled with the memory interface. The plurality of multi-level memory cells include a first page and a second page. The first page is associated with bits of a first significance. The second page is associated with bits of a second significance. The circuitry is configured to map a first portion of an encoded data sector to the first page and map a second portion of the encoded data sector to the second page. The first portion excludes the second portion and the second portion excludes the first portion such that each of the first page and the second page contains different data from the encoded data sector.
    Type: Application
    Filed: August 29, 2014
    Publication date: December 18, 2014
    Inventors: Shashi Kiran Chilappagari, Xueshi Yang, Gregory Burd
  • Patent number: 8913437
    Abstract: A method includes selecting a first memory cell located along a first bit line and a first word line of a memory array. The method further includes selecting a second memory cell located along (i) the first word line, (ii) a second word line that is adjacent to the first word line, or (iii) a second bit line that is adjacent to the first bit line. A location of the second memory cell is selected based on a predetermined sequence of programming the memory cells. The method further includes writing data in the first memory cell, subsequently writing data in the second memory cell, and reading the first memory cell and the second memory cell. The method further includes detecting one or more states of the second memory causing interference to the first memory cell.
    Type: Grant
    Filed: December 13, 2012
    Date of Patent: December 16, 2014
    Assignee: Marvell World Trade Ltd.
    Inventors: Shashi Kiran Chilappagari, Zhengang Chen, Gregory Burd
  • Publication number: 20140344647
    Abstract: A controller for a nonvolatile memory device includes a transfer control module and a decoder module. The transfer control module is configured to request a read of data from a flash memory module. The data to be read includes data corresponding to a first codeword. The transfer control module is configured to receive hard decisions corresponding to the first codeword from the flash memory module. The transfer control module is configured to receive soft information corresponding to the first codeword from the flash memory module. Both the hard decisions corresponding to the first codeword and the soft information corresponding to the first codeword are received without receiving any intervening hard decisions or soft information corresponding to another codeword. The decoder module is configured to decode the first codeword using the hard decisions and the soft information corresponding to the first codeword.
    Type: Application
    Filed: May 1, 2014
    Publication date: November 20, 2014
    Applicant: Marvell World Trade LTD.
    Inventors: Shashi Kiran Chilappagari, Gregory Burd
  • Patent number: 8885415
    Abstract: A system including a read module to perform a first read operation to determine a state of a memory cell, and in response to a first failure to decode data read from the memory cell, perform second and third read operations to determine the state of the memory cell. The memory cell has first and second threshold voltages when programmed to first and second states, respectively. A shift detection module detects, in response to a second failure to decode data read from the memory cell in the second and third read operations, a shift in a distribution of at least one of the first and second threshold voltages. A binning module divides the distribution into a plurality of bins. A log-likelihood ratio (LLR) module generates LLRs for the plurality of bins based on a variance of the distribution and adjusts the LLRs based on an amount of the shift.
    Type: Grant
    Filed: September 9, 2013
    Date of Patent: November 11, 2014
    Assignee: Marvell World Trade Ltd.
    Inventors: Shashi Kiran Chilappagari, Xueshi Yang
  • Patent number: 8875000
    Abstract: Systems and methods for encoding and decoding for communications or storage systems utilizing coded modulation are provided. A first portion of data is encoded with a first at least one encoding scheme. A second portion of the data id encoded with a second encoding scheme. A coset is selected from a plurality of cosets based at least in part on the encoded first portion of the data, where the plurality of cosets corresponds to a partition of a signal constellation. A signal vector is selected within the selected coset based at least in part on the encoded second portion of the data.
    Type: Grant
    Filed: October 31, 2011
    Date of Patent: October 28, 2014
    Assignee: Marvell World Trade Ltd.
    Inventors: Shashi Kiran Chilappagari, Xueshi Yang