Patents by Inventor Chi-Ming Wang

Chi-Ming Wang 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: 6977844
    Abstract: In a non-volatile memory, the displacement current generated in non-selected word lines that results when the voltage levels on an array's bit lines are changed can result in disturbs. Techniques for reducing these currents are presented. In a first aspect, the number of cells being simultaneously programmed on a word line is reduced. In a non-volatile memory where an array of memory cells is composed of a number of units, and the units are combined into planes that share common word lines, the simultaneous programming of units within the same plane is avoided. Multiple units may be programmed in parallel, but these are arranged to be in separate planes. This is done by selecting the number of units to be programmed in parallel and their order such that all the units programmed together are from distinct planes, by comparing the units to be programmed to see if any are from the same plane, or a combination of these.
    Type: Grant
    Filed: February 8, 2005
    Date of Patent: December 20, 2005
    Assignee: SanDisk Corporation
    Inventors: Daniel C. Guterman, George Samachisa, Brian Murphy, Chi-Ming Wang, Khandker N. Quader
  • Publication number: 20050219896
    Abstract: Systems and methods in accordance with various embodiments can provide for reduced program disturb in non-volatile semiconductor memory. In one embodiment, select memory cells such as those connected to a last word line of a NAND string are programmed using one or more program verify levels or voltages that are different than a corresponding level used to program other cells or word lines. One exemplary embodiment includes using a lower threshold voltage verify level for select physical states when programming the last word line to be programmed for a string during a program operation. Another embodiment includes applying a lower program voltage to program memory cells of the last word line to select physical states. Additional read levels are established for reading the states programmed using lower verify levels in some exemplary implementations.
    Type: Application
    Filed: April 6, 2004
    Publication date: October 6, 2005
    Inventors: Jian Chen, Chi-Ming Wang
  • Publication number: 20050146933
    Abstract: In a non-volatile memory, the displacement current generated in non-selected word lines that results when the voltage levels on an array's bit lines are changed can result in disturbs. Techniques for reducing these currents are presented. In a first aspect, the number of cells being simultaneously programmed on a word line is reduced. In a non-volatile memory where an array of memory cells is composed of a number of units, and the units are combined into planes that share common word lines, the simultaneous programming of units within the same plane is avoided. Multiple units may be programmed in parallel, but these are arranged to be in separate planes. This is done by selecting the number of units to be programmed in parallel and their order such that all the units programmed together are from distinct planes, by comparing the units to be programmed to see if any are from the same plane, or a combination of these.
    Type: Application
    Filed: February 8, 2005
    Publication date: July 7, 2005
    Inventors: Daniel Guterman, George Samachisa, Brian Murphy, Chi-Ming Wang, Khandker Quader
  • Publication number: 20050101236
    Abstract: A current-limited latch circuit is used within a nonvolatile memory integrated circuit for decoding, programming, erase, and other operations. In one implementation, there are a number of latches connected together in parallel between two power supply lines. A current mirroring scheme limits current supplied to the latch. This reduces a difference of the two supplies, positive voltage, ground, or negative voltages, during data changes. The circuit provides smaller device sizes and fast speeds when data changes in the latch, while also providing lower power consumption. The technique provides greater benefits as the voltage difference between the two power supplies is greater.
    Type: Application
    Filed: December 20, 2004
    Publication date: May 12, 2005
    Applicant: SanDisk Corporation
    Inventors: Chi-Ming Wang, Kuo-Lung Chen, Shouchang Tsao
  • Patent number: 6888752
    Abstract: In a non-volatile memory, the displacement current generated in non-selected word lines that results when the voltage levels on an array's bit lines are changed can result in disturbs. Techniques for reducing these currents are presented. In a first aspect, the number of cells being simultaneously programmed on a word line is reduced. In a non-volatile memory where an array of memory cells is composed of a number of units, and the units are combined into planes that share common word lines, the simultaneous programming of units within the same plane is avoided. Multiple units may be programmed in parallel, but these are arranged to be in separate planes. This is done by selecting the number of units to be programmed in parallel and their order such that all the units programmed together are from distinct planes, by comparing the units to be programmed to see if any are from the same plane, or a combination of these.
    Type: Grant
    Filed: July 1, 2003
    Date of Patent: May 3, 2005
    Assignee: SanDisk Corporation
    Inventors: John S. Mangan, Daniel C. Guterman, George Samachisa, Brian Murphy, Chi-Ming Wang, Khandker N. Quader
  • Patent number: 6801454
    Abstract: Techniques for producing and utilizing temperature compensated voltages to accurately read signals (e.g., voltages) representing data stored in memory cells of a memory system are disclosed. The memory system is, for example, a memory card. The magnitude of the temperature compensation can be varied or controlled in accordance with a temperature coefficient. These techniques are particularly well suited for used with memory cells that provide multiple levels of storage.
    Type: Grant
    Filed: October 1, 2002
    Date of Patent: October 5, 2004
    Assignee: SanDisk Corporation
    Inventors: Yongliang Wang, Raul A. Cernea, Chi-Ming Wang
  • Publication number: 20040109354
    Abstract: A current-limited latch circuit is used within a nonvolatile memory integrated circuit for decoding, programming, erase, and other operations. In one implementation, there are a number of latches connected together in parallel between two power supply lines. A current mirroring scheme limits current supplied to the latch. This reduces a difference of the two supplies, positive voltage, ground, or negative voltages, during data changes. The circuit provides smaller device sizes and fast speeds when data changes in the latch, while also providing lower power consumption. The technique provides greater benefits as the voltage difference between the two power supplies is greater.
    Type: Application
    Filed: December 6, 2002
    Publication date: June 10, 2004
    Applicant: SanDisk Corporation
    Inventors: Chi-Ming Wang, Kuo-Lung Chen, Shouchang Tsao
  • Publication number: 20040105311
    Abstract: Floating gate memories such as EEPROM and flash EEPROM have the memory state of a memory cell thereof determined by sensing the conduction current of the cell. Inherent noise fluctuations in the conduction current during sensing are canceled out by averaging the sensing over a predetermined period of time. In one embodiment, as an integral part of the averaging process, the averaged conduction current is obtained directly as a digital memory state. Accuracy in sensing is therefore greatly improved by avoiding sensing noise with the current and avoiding having to resolve its memory state in the analog domain by comparison with another noisy reference current. In another embodiment, conventional sensing techniques are improved when sensing is made by comparison with a reference current by means of a symmetric, switched or non-switched capacitor differential amplifier.
    Type: Application
    Filed: November 12, 2003
    Publication date: June 3, 2004
    Inventors: Raul-Adrian Cernea, Rushyah Tang, Douglas Lee, Chi-Ming Wang, Daniel Guterman
  • Patent number: 6717851
    Abstract: In a non-volatile memory, the displacement current generated in non-selected word lines that results when the voltage levels on an array's bit lines are changed can result in disturbs. Techniques for reducing these currents are presented. In a first aspect, the number of cells being simultaneously programmed on a word line is reduced. In a non-volatile memory where an array of memory cells is composed of a number of units, and the units are combined into planes that share common word lines, the simultaneous programming of units within the same plane is avoided. Multiple units may be programmed in parallel, but these are arranged to be in separate planes. This is done by selecting the number of units to be programmed in parallel and their order such that all the units programmed together are from distinct planes, by comparing the units to be programmed to see if any are from the same plane, or a combination of these.
    Type: Grant
    Filed: January 10, 2001
    Date of Patent: April 6, 2004
    Assignee: SanDisk Corporation
    Inventors: John S. Mangan, Daniel C. Guterman, George Samachisa, Brian Murphy, Chi-Ming Wang, Khandker N. Quader
  • Publication number: 20040062085
    Abstract: Techniques for producing and utilizing temperature compensated voltages to accurately read signals (e.g., voltages) representing data stored in memory cells of a memory system are disclosed. The memory system is, for example, a memory card. The magnitude of the temperature compensation can be varied or controlled in accordance with a temperature coefficient. These techniques are particularly well suited for used with memory cells that provide multiple levels of storage.
    Type: Application
    Filed: October 1, 2002
    Publication date: April 1, 2004
    Applicant: SanDisk Corporation
    Inventors: Yongliang Wang, Raul A. Cernea, Chi-Ming Wang
  • Publication number: 20040027865
    Abstract: In a non-volatile memory, the displacement current generated in non-selected word lines that results when the voltage levels on an array's bit lines are changed can result in disturbs. Techniques for reducing these currents are presented. In a first aspect, the number of cells being simultaneously programmed on a word line is reduced. In a non-volatile memory where an array of memory cells is composed of a number of units, and the units are combined into planes that share common word lines, the simultaneous programming of units within the same plane is avoided. Multiple units may be programmed in parallel, but these are arranged to be in separate planes. This is done by selecting the number of units to be programmed in parallel and their order such that all the units programmed together are from distinct planes, by comparing the units to be programmed to see if any are from the same plane, or a combination of these.
    Type: Application
    Filed: July 1, 2003
    Publication date: February 12, 2004
    Inventors: John S. Mangan, Daniel C. Guterman, George Samachisa, Brian Murphy, Chi-Ming Wang, Khandker N. Quader
  • Patent number: 6661708
    Abstract: Floating gate memories such as EEPROM and flash EEPROM have the memory state of a memory cell thereof determined by sensing the conduction current of the cell. Inherent noise fluctuations in the conduction current during sensing are canceled out by averaging the sensing over a predetermined period of time. In one embodiment, as an integral part of the averaging process, the averaged conduction current is obtained directly as a digital memory state. Accuracy in sensing is therefore greatly improved by avoiding sensing noise with the current and avoiding having to resolve its memory state in the analog domain by comparison with another noisy reference current. In another embodiment, conventional sensing techniques are improved when sensing is made by comparison with a reference current by means of a symmetric, switched or non-switched capacitor differential amplifier.
    Type: Grant
    Filed: November 7, 2002
    Date of Patent: December 9, 2003
    Assignee: SanDisk Corporation
    Inventors: Raul-Adrian Cernea, Rushyah Tang, Douglas Lee, Chi-Ming Wang, Daniel Guterman
  • Patent number: 6570785
    Abstract: In a non-volatile memory, the displacement current generated in non-selected word lines that results when the voltage levels on an array's bit lines are changed can result in disturbs. Techniques for reducing these currents are presented. In a first aspect, the number of cells being simultaneously programmed on a word line is reduced. In a non-volatile memory where an array of memory cells is composed of a number of units, and the units are combined into planes that share common word lines, the simultaneous programming of units within the same plane is avoided. Multiple units may be programmed in parallel, but these are arranged to be in separate planes. This is done by selecting the number of units to be programmed in parallel and their order such that all the units programmed together are from distinct planes, by comparing the units to be programmed to see if any are from the same plane, or a combination of these.
    Type: Grant
    Filed: October 31, 2000
    Date of Patent: May 27, 2003
    Assignee: SanDisk Corporation
    Inventors: John S. Mangan, Daniel C. Guterman, George Samachisa, Brian Murphy, Chi-Ming Wang
  • Publication number: 20030072177
    Abstract: Floating gate memories such as EEPROM and flash EEPROM have the memory state of a memory cell thereof determined by sensing the conduction current of the cell. Inherent noise fluctuations in the conduction current during sensing are canceled out by averaging the sensing over a predetermined period of time. In one embodiment, as an integral part of the averaging process, the averaged conduction current is obtained directly as a digital memory state. Accuracy in sensing is therefore greatly improved by avoiding sensing noise with the current and avoiding having to resolve its memory state in the analog domain by comparison with another noisy reference current. In another embodiment, conventional sensing techniques are improved when sensing is made by comparison with a reference current by means of a symmetric, switched or non-switched capacitor differential amplifier.
    Type: Application
    Filed: November 7, 2002
    Publication date: April 17, 2003
    Inventors: Raul-Adrian Cernea, Rushyah Tang, Douglas Lee, Chi-Ming Wang, Daniel Guterman
  • Patent number: 6490200
    Abstract: Floating gate memories such as EEPROM and flash EEPROM have the memory state of a memory cell thereof determined by sensing the conduction current of the cell. Inherent noise fluctuations in the conduction current during sensing are canceled out by averaging the sensing over a predetermined period of time. In one embodiment, as an integral part of the averaging process, the averaged conduction current is obtained directly as a digital memory state. Accuracy in sensing is therefore greatly improved by avoiding sensing noise with the current and avoiding having to resolve its memory state in the analog domain by comparison with another noisy reference current. In another embodiment, conventional sensing techniques are improved when sensing is made by comparison with a reference current by means of a symmetric, switched or non-switched capacitor differential amplifier.
    Type: Grant
    Filed: August 7, 2001
    Date of Patent: December 3, 2002
    Assignee: SanDisk Corporation
    Inventors: Raul-Adrian Cernea, Rushyah Tang, Douglas Lee, Chi-Ming Wang, Daniel Guterman
  • Publication number: 20020114184
    Abstract: Techniques for producing and supplying various voltage levels within a memory system having multiple memory blocks (e.g., memory chips) are described. The various voltage levels can be produced by voltage generation circuitry (e.g., charge pump and/or regulator circuitry) within the memory system. The various voltage levels can be supplied to the multiple memory blocks through a power bus. According to one aspect, charge pump and/or regulator circuits are provided within at most one of the memory blocks of a memory system (unless back-ups are provided for fault tolerance), and a power bus is used to distribute the generated voltage levels to other of the memory blocks. According to another aspect, a memory controller generates multiple supply voltage levels that are distributed (e.g., via a power bus) to each of the memory blocks.
    Type: Application
    Filed: February 16, 2001
    Publication date: August 22, 2002
    Applicant: SanDisk Corporation
    Inventors: Geoffrey Steven Gongwer, Kevin M. Conley, Chi-Ming Wang, Yong Liang Wang, Raul Adrian Cernea
  • Patent number: 6434044
    Abstract: Techniques for producing and supplying various voltage levels within a memory system having multiple memory blocks (e.g., memory chips) are described. The various voltage levels can be produced by voltage generation circuitry (e.g., charge pump and/or regulator circuitry) within the memory system. The various voltage levels can be supplied to the multiple memory blocks through a power bus. According to one aspect, charge pump and/or regulator circuits are provided within at most one of the memory blocks of a memory system (unless back-ups are provided for fault tolerance), and a power bus is used to distribute the generated voltage levels to other of the memory blocks. According to another aspect, a memory controller generates multiple supply voltage levels that are distributed (e.g., via a power bus) to each of the memory blocks.
    Type: Grant
    Filed: February 16, 2001
    Date of Patent: August 13, 2002
    Assignee: SanDisk Corporation
    Inventors: Geoffrey Steven Gongwer, Kevin M. Conley, Chi-Ming Wang, Yong Liang Wang, Raul Adrian Cernea
  • Publication number: 20020051384
    Abstract: Floating gate memories such as EEPROM and flash EEPROM have the memory state of a memory cell thereof determined by sensing the conduction current of the cell. Inherent noise fluctuations in the conduction current during sensing are canceled out by averaging the sensing over a predetermined period of time. In one embodiment, as an integral part of the averaging process, the averaged conduction current is obtained directly as a digital memory state. Accuracy in sensing is therefore greatly improved by avoiding sensing noise with the current and avoiding having to resolve its memory state in the analog domain by comparison with another noisy reference current. In another embodiment, conventional sensing techniques are improved when sensing is made by comparison with a reference current by means of a symmetric, switched or non-switched capacitor differential amplifier.
    Type: Application
    Filed: August 7, 2001
    Publication date: May 2, 2002
    Applicant: SanDisk Corporation
    Inventors: Raul-Adrian Cernea, Rushyah Tang, Douglas Lee, Chi-Ming Wang, Daniel Guterman
  • Publication number: 20020051383
    Abstract: In a non-volatile memory, the displacement current generated in non-selected word lines that results when the voltage levels on an array's bit lines are changed can result in disturbs. Techniques for reducing these currents are presented. In a first aspect, the number of cells being simultaneously programmed on a word line is reduced. In a non-volatile memory where an array of memory cells is composed of a number of units, and the units are combined into planes that share common word lines, the simultaneous programming of units within the same plane is avoided. Multiple units may be programmed in parallel, but these are arranged to be in separate planes. This is done by selecting the number of units to be programmed in parallel and their order such that all the units programmed together are from distinct planes, by comparing the units to be programmed to see if any are from the same plane, or a combination of these.
    Type: Application
    Filed: January 10, 2001
    Publication date: May 2, 2002
    Inventors: John S. Mangan, Daniel C. Guterman, George Samachisa, Brian Murphy, Chi-Ming Wang, Khandker N. Quader
  • Patent number: 6282120
    Abstract: Floating gate memories such as EEPROM and flash EEPROM have the memory state of a memory cell thereof determined by sensing the conduction current of the cell Inherent noise fluctuations in the conduction current during sensing are canceled out by averaging the sensing over a predetermined period of time. In one embodiment, as an integral part of the averaging process, the averaged conduction current is obtained directly as a digital memory state. Accuracy in sensing is therefore greatly improved by avoiding sensing noise with the current and avoiding having to resolve its memory state in the analog domain by comparison with another noisy reference current. In another embodiment, conventional sensing techniques are improved when sensing is made by comparison with a reference current by means of a symmetric, switched or non-switched capacitor differential amplifier.
    Type: Grant
    Filed: March 27, 2000
    Date of Patent: August 28, 2001
    Assignee: SanDisk Corporation
    Inventors: Raul-Adrian Cernea, Rushyah Tang, Douglas Lee, Chi-Ming Wang, Daniel Guterman