Patents by Inventor Mohan Vamsi Dunga
Mohan Vamsi Dunga 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: 12633353Abstract: An apparatus includes control circuits configured to connect to a plurality of nonvolatile memory cells. The one or more control circuits are configured to apply read voltages on a plurality of word lines connected to the nonvolatile memory cells, ramp down from the read voltages to subsequent voltages such that voltage on a word line transitions through a voltage that is below a subsequent voltage by a negative kick voltage. The one or more control circuits are further configured to apply a first negative kick voltage to ramp down from a read voltage on a first word line and apply a second negative kick voltage to ramp down from the read voltage on a second word line.Type: GrantFiled: April 22, 2024Date of Patent: May 19, 2026Assignee: Sandisk Technologies, Inc.Inventors: Abhijith Prakash, Qinghua Zhao, Mohan Vamsi Dunga
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Patent number: 12592264Abstract: Multi-stage charge pumps use a modular structure in which each stage include a pair of legs, or current paths, between the stage input and the stage output. Each leg includes a stage boosting capacitor having a first plate connected to the current path and a second plate connected to receive one of a pair of non-overlapping clock signals. Each leg has an NMOS charge transfer switch connected between the stage input and the first plate of the stage boosting capacitor and a PMOS charge transfer switch connected between the first plate of the stage boosting capacitor and the stage output. To reduce charge pump area, the NMOS and PMOS charge transfer switches are formed to have a same resistance value when in an on state, where to achieve this the NMOS charge transfer switches are formed with wider control gates than the PMOS charge transfer switches.Type: GrantFiled: June 28, 2024Date of Patent: March 31, 2026Assignee: Sandisk Technologies, Inc.Inventors: Ankit Rehani, Chao Qin, Mohan Vamsi Dunga
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Publication number: 20260088092Abstract: Technology for operating word line switch (WLSW) transistors that are configured to provide voltages to word lines in non-volatile storage such as NAND. Each WLSW transistor has a source terminal that may be connected to a word line in order to provide an operating voltage to that word line. In an aspect, voltages are applied to a WLSW transistor to charge an unselected word line in an unselected block to a pre-charge voltage during a program operation of a selected word line in a selected block. This pre-charge voltage may remain on the source terminal of the WLSW transistor that is connected to the unselected word line while a neighboring WLSW transistor provides a program voltage to the selected word line in the selected block. Therefore, the voltage difference between the source terminals of the neighboring WLSW transistors is reduced, which reduces leakage current between these two WLSW transistors.Type: ApplicationFiled: September 24, 2024Publication date: March 26, 2026Applicant: Sandisk Technologies, Inc.Inventors: Qinghua Zhao, Mohan Vamsi Dunga, Gwang Yeong Stanley Jeong
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Publication number: 20260082703Abstract: Control circuits are configured to receive an input voltage through bond pads located on a surface of a die and generate supply voltages from the input voltage in a plurality of charge pumps located in a charge pump area of the die. The control circuits are further configured to provide the supply voltages to a plurality of voltage regulation circuits, each voltage regulation circuit located in a respective area of the die that corresponds to a portion of the nonvolatile memory array and generate a plurality of corresponding regulated voltages at each of the plurality of voltage regulation circuits for the corresponding portion of the nonvolatile memory array.Type: ApplicationFiled: September 17, 2024Publication date: March 19, 2026Applicant: Sandisk Technologies, Inc.Inventors: Ankit Rehani, V.S.N.K. Chaitanya G, Indra Kumar K V, Mohan Vamsi Dunga, Naoki Ookuma, Bandimata Nagaraj
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Patent number: 12518810Abstract: A memory device is provided and includes a memory block that has a plurality of memory cells that are arranged in a plurality of word lines. The memory device also includes a plurality of word line switch transistors that are electrically coupled with the plurality of word lines. Some of the word line switch transistors have a first width and some of the word line switch transistors have a second width that is different than the first width. By providing the word line switch transistors with different widths, the size of a word line switch area in the memory device can be optimized.Type: GrantFiled: August 1, 2023Date of Patent: January 6, 2026Assignee: Sandisk Technologies, Inc.Inventors: Mohan Vamsi Dunga, Xiang Yang, Keyur Payak
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Publication number: 20260004822Abstract: Multi-stage charge pumps use a modular structure in which each stage include a pair of legs, or current paths, between the stage input and the stage output. Each leg includes a stage boosting capacitor having a first plate connected to the current path and a second plate connected to receive one of a pair of non-overlapping clock signals. Each leg has an NMOS charge transfer switch connected between the stage input and the first plate of the stage boosting capacitor and a PMOS charge transfer switch connected between the first plate of the stage boosting capacitor and the stage output. To reduce charge pump area, the NMOS and PMOS charge transfer switches are formed to have a same resistance value when in an on state, where to achieve this the NMOS charge transfer switches are formed with wider control gates than the PMOS charge transfer switches.Type: ApplicationFiled: June 28, 2024Publication date: January 1, 2026Applicant: Sandisk Technologies, Inc.Inventors: Ankit Rehani, Chao Qin, Mohan Vamsi Dunga
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Publication number: 20250329393Abstract: An apparatus includes control circuits configured to connect to a plurality of nonvolatile memory cells. The one or more control circuits are configured to apply read voltages on a plurality of word lines connected to the nonvolatile memory cells, ramp down from the read voltages to subsequent voltages such that voltage on a word line transitions through a voltage that is below a subsequent voltage by a negative kick voltage. The one or more control circuits are further configured to apply a first negative kick voltage to ramp down from a read voltage on a first word line and apply a second negative kick voltage to ramp down from the read voltage on a second word line.Type: ApplicationFiled: April 22, 2024Publication date: October 23, 2025Applicant: SanDisk Technologies LLCInventors: Abhijith Prakash, Qinghua Zhao, Mohan Vamsi Dunga
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Publication number: 20250210108Abstract: Technology for operating word line switch transistors in a memory system. A memory system provides for separate control of the voltage to the gates of the word line switch transistors and a voltage to a well in which the word line switch transistors reside. This allows for a negative voltage to be applied to the gates and/or the well. However, if desired, a non-negative voltage (e.g., 0V) may be applied to the gates or the well.Type: ApplicationFiled: December 20, 2023Publication date: June 26, 2025Applicant: Western Digital Technologies, Inc.Inventors: Qinghua Zhao, Gwang Yeong Stanley Jeong, Sichang Qin, Sudarshan Narayanan, Mohan Vamsi Dunga
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Publication number: 20250006244Abstract: A memory apparatus and method of operation are provided. The apparatus includes memory cells each connected to one of a plurality of word lines and disposed in memory holes and configured to retain a threshold voltage corresponding to one of a plurality of data states. A control means is coupled to the plurality of word lines and the memory holes. The control means is configured to apply a plurality of pulses of a program voltage increasing in magnitude by a program step amount to selected ones of the plurality of word lines while applying at least one pass voltage to unselected ones of the plurality of word lines during a plurality of programming loops of a programming operation. The control means is also configured to adjust the at least one pass voltage based on the program voltage.Type: ApplicationFiled: August 14, 2023Publication date: January 2, 2025Applicant: Western Digital Technologies, Inc.Inventors: Mohan Vamsi Dunga, Xiang Yang
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Publication number: 20240386930Abstract: A memory device is provided and includes a memory block that has a plurality of memory cells that are arranged in a plurality of word lines. The memory device also includes a plurality of word line switch transistors that are electrically coupled with the plurality of word lines. Some of the word line switch transistors have a first width and some of the word line switch transistors have a second width that is different than the first width. By providing the word line switch transistors with different widths, the size of a word line switch area in the memory device can be optimized.Type: ApplicationFiled: August 1, 2023Publication date: November 21, 2024Applicant: Western Digital Technologies, Inc.Inventors: Mohan Vamsi Dunga, Xiang Yang, Keyur Payak
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Patent number: 10818366Abstract: A storage device with a charge trapping (CT) based memory may include improved data retention performance. Data retention problems, such as charge loss in CT memory may increase for a particular programmed state when a neighboring state is at erased state. Modifying the erase state with post write erase conditioning (PWEC) by pushing up deeply erased states can reduce the lateral charge movement and improve high temperature data retention. In particular, the erase state may be reprogrammed such that the erase distribution is tighter with a higher voltage.Type: GrantFiled: January 15, 2020Date of Patent: October 27, 2020Assignee: Western Digital Technologies, Inc.Inventors: Mohan Vamsi Dunga, Changyuan Chen, Biswajit Ray
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Publication number: 20200152281Abstract: A storage device with a charge trapping (CT) based memory may include improved data retention performance. Data retention problems, such as charge loss in CT memory may increase for a particular programmed state when a neighboring state is at erased state. Modifying the erase state with post write erase conditioning (PWEC) by pushing up deeply erased states can reduce the lateral charge movement and improve high temperature data retention. In particular, the erase state may be reprogrammed such that the erase distribution is tighter with a higher voltage.Type: ApplicationFiled: January 15, 2020Publication date: May 14, 2020Inventors: Mohan Vamsi DUNGA, Changyuan CHEN, Biswajit RAY
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Patent number: 10553294Abstract: A storage device with a charge trapping (CT) based memory may include improved data retention performance. Data retention problems, such as charge loss in CT memory may increase for a particular programmed state when a neighboring state is at erased state. Modifying the erase state with post write erase conditioning (PWEC) by pushing up deeply erased states can reduce the lateral charge movement and improve high temperature data retention. In particular, the erase state may be reprogrammed such that the erase distribution is tighter with a higher voltage.Type: GrantFiled: January 25, 2019Date of Patent: February 4, 2020Assignee: Western Digital Technologies, Inc.Inventors: Mohan Vamsi Dunga, Changyuan Chen, Biswajit Ray
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Patent number: 10541031Abstract: A program circuit may two-dimensionally program data into cells by applying different selected bit line or channel voltages to different bit lines or channels located in different bit line zones of a block during a program operation. The block may be further separated or divided into word line zones. The program circuit may adjust the different bit line or channel voltages as it programs in different word line zones of the block. In accordance with the two-dimensional programming, the program circuit may perform single-pulse program-only SLC program operations.Type: GrantFiled: June 15, 2018Date of Patent: January 21, 2020Assignee: SANDISK TECHNOLOGIES LLCInventors: Mohan Vamsi Dunga, Piyush Dak, Pitamber Shukla
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Publication number: 20190385680Abstract: A program circuit may two-dimensionally program data into cells by applying different selected bit line or channel voltages to different bit lines or channels located in different bit line zones of a block during a program operation. The block may be further separated or divided into word line zones. The program circuit may adjust the different bit line or channel voltages as it programs in different word line zones of the block. In accordance with the two-dimensional programming, the program circuit may perform single-pulse program-only SLC program operations.Type: ApplicationFiled: June 15, 2018Publication date: December 19, 2019Applicant: SanDisk Technologies LLCInventors: Mohan Vamsi Dunga, Piyush Dak, Pitamber Shukla
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Patent number: 10460814Abstract: Embodiments of the present disclosure generally relate to non-volatile memory devices, such as flash memory, and sensing operation methods including locking out high conduction current memory cells of the memory devices. In one embodiment, a method of sensing a plurality of memory cells in an array includes conducting a lower page read of one or more demarcation threshold voltages. Each memory cell is programmable to a threshold voltage corresponding to one of multiple memory states. A middle page read of one or more demarcation threshold voltages is conducted. Memory cells identified from the lower page read are selectively locked out during the middle page read. An upper page read of one or more demarcation threshold voltages is conducted. Memory cells identified from a prior page read are selectively locked out during the upper page read.Type: GrantFiled: December 12, 2017Date of Patent: October 29, 2019Assignee: WESTERN DIGITAL TECHNOLOGIES, INC.Inventors: Piyush Dak, Mohan Vamsi Dunga, Pitamber Shukla
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Publication number: 20190180823Abstract: Embodiments of the present disclosure generally relate to non-volatile memory devices, such as flash memory, and sensing operation methods including locking out high conduction current memory cells of the memory devices. In one embodiment, a method of sensing a plurality of memory cells in an array includes conducting a lower page read of one or more demarcation threshold voltages. Each memory cell is programmable to a threshold voltage corresponding to one of multiple memory states. A middle page read of one or more demarcation threshold voltages is conducted. Memory cells identified from the lower page read are selectively locked out during the middle page read. An upper page read of one or more demarcation threshold voltages is conducted. Memory cells identified from a prior page read are selectively locked out during the upper page read.Type: ApplicationFiled: December 12, 2017Publication date: June 13, 2019Inventors: Piyush DAK, Mohan Vamsi DUNGA, Pitamber SHUKLA
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Patent number: 10304559Abstract: A device is disclosed that includes a data write engine configured to store data into a block of a memory. The device also includes a post-write read engine configured to adjust a read voltage responsive to an output of the temperature sensor and to read stored data from the block based on the adjusted read voltage to verify integrity of the data. The device also includes a block manager configured to initiate a corrective operation responsive to an error characteristic of the data read from the block.Type: GrantFiled: December 30, 2016Date of Patent: May 28, 2019Assignee: Western Digital Technologies, Inc.Inventors: Himanshu Hemant Naik, Biswajit Ray, Mohan Vamsi Dunga, Changyuan Chen
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Publication number: 20190156902Abstract: A storage device with a charge trapping (CT) based memory may include improved data retention performance. Data retention problems, such as charge loss in CT memory may increase for a particular programmed state when a neighboring state is at erased state. Modifying the erase state with post write erase conditioning (PWEC) by pushing up deeply erased states can reduce the lateral charge movement and improve high temperature data retention. In particular, the erase state may be reprogrammed such that the erase distribution is tighter with a higher voltage.Type: ApplicationFiled: January 25, 2019Publication date: May 23, 2019Inventors: Mohan Vamsi DUNGA, Changyuan CHEN, Biswajit RAY
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Patent number: 10269439Abstract: A storage device with a charge trapping (CT) based memory may include improved data retention performance. Data retention problems, such as charge loss in CT memory may increase for a particular programmed state when a neighboring state is at erased state. Modifying the erase state with post write erase conditioning (PWEC) by pushing up deeply erased states can reduce the lateral charge movement and improve high temperature data retention. In particular, the erase state may be reprogrammed such that the erase distribution is tighter with a higher voltage.Type: GrantFiled: March 28, 2017Date of Patent: April 23, 2019Assignee: Western Digital Technologies, Inc.Inventors: Mohan Vamsi Dunga, Changyuan Chen, Biswajit Ray