Patents by Inventor Shigekazu Yamada

Shigekazu Yamada 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).

  • Publication number: 20120092933
    Abstract: Memory devices and erase methods for memories are disclosed, such as those adapted to discharge an erase voltage from a memory block while protecting low voltage string select gate transistors by maintaining the string select gate transistors in a turned on state during discharge.
    Type: Application
    Filed: December 20, 2011
    Publication date: April 19, 2012
    Inventors: Shigekazu YAMADA, Tomoharu Tanaka
  • Publication number: 20120014185
    Abstract: An integrated circuit bit line driver system includes a plurality of bit line drivers coupled to respective bit lines of an array of non-volatile memory cells. Each of the bit line drivers includes a bias transistor through which an input signal is coupled to the respective bit line. The bit line driver system includes a bias voltage circuit that generates a bias voltage that is coupled to the respective gates of the bias transistors. The bias voltage circuit initially accelerates the charging of the transistor gates, and subsequently completes charging the gates at a slower rate. The bias voltage is generated using a diode-coupled transistor having electrical characteristics the match those of the bias transistors so that the bias voltage varies with process or temperature variations of the integrated circuit in the same manner as the threshold voltage of the bias transistors vary with process or temperature variations.
    Type: Application
    Filed: September 22, 2011
    Publication date: January 19, 2012
    Applicant: Micron Technology, Inc.
    Inventor: Shigekazu Yamada
  • Patent number: 8089816
    Abstract: Memory devices and erase methods for memories are disclosed, such as those adapted to discharge an erase voltage from a memory block while protecting low voltage string select gate transistors by maintaining the string select gate transistors in a turned on state during discharge.
    Type: Grant
    Filed: June 3, 2009
    Date of Patent: January 3, 2012
    Assignee: Micron Technology, Inc.
    Inventors: Shigekazu Yamada, Tomoharu Tanaka
  • Publication number: 20110286282
    Abstract: Semiconductor memory devices and methods include a flash memory cell array fabricated in a well, with memory cells in the same column connected to each other in series and connected to a respective bit line. The memory devices also include a column decoder, a data register buffer unit, a row decoder, an erase control unit, and an input/output buffer unit. In one or more embodiments, the erase control unit applies voltages to the well to erase the memory cells in a manner that avoids breaking down p-n junctions formed by transistors fabricated in the well. In another embodiment, high voltage transistors are used to selectively isolate the bit lines from and couple the bit lines to a peripheral circuit in pairs so that each high voltage transistor is shared by two bit lines.
    Type: Application
    Filed: July 29, 2011
    Publication date: November 24, 2011
    Applicant: Micron Technology, Inc.
    Inventors: Shigekazu Yamada, Tomoharu Tanaka
  • Patent number: 8045395
    Abstract: An integrated circuit bit line driver system includes a plurality of bit line drivers coupled to respective bit lines of an array of non-volatile memory cells. Each of the bit line drivers includes a bias transistor through which an input signal is coupled to the respective bit line. The bit line driver system includes a bias voltage circuit that generates a bias voltage that is coupled to the respective gates of the bias transistors. The bias voltage circuit initially accelerates the charging of the transistor gates, and subsequently completes charging the gates at a slower rate. The bias voltage is generated using a diode-coupled transistor having electrical characteristics the match those of the bias transistors so that the bias voltage varies with process or temperature variations of the integrated circuit in the same manner as the threshold voltage of the bias transistors vary with process or temperature variations.
    Type: Grant
    Filed: May 14, 2010
    Date of Patent: October 25, 2011
    Assignee: Micron Technology, Inc.
    Inventor: Shigekazu Yamada
  • Publication number: 20110249503
    Abstract: Methods for programming select gates, memory devices, and memory systems are disclosed. In one such method for programming, a program inhibit voltage is transferred from a source line to unselected bit lines. Bit line-to-bit line capacitance, between the unselected bit lines and selected bit lines to be program inhibited, boosts the bit line voltage of the selected, inhibited bit lines to a target inhibit voltage. In one embodiment, the voltage on the selected, inhibited bit line can be increased in a plurality of inhibit steps whereby either one, two, or all of the steps can be used during the programming of unprogrammed select gates.
    Type: Application
    Filed: April 8, 2010
    Publication date: October 13, 2011
    Inventors: Shigekazu Yamada, Aaron Yip
  • Patent number: 8000151
    Abstract: Semiconductor memory devices and methods include a flash memory cell array fabricated in a well, with memory cells in the same column connected to each other in series and connected to a respective bit line. The memory devices also include a column decoder, a data register buffer unit, a row decoder, an erase control unit, and an input/output buffer unit. In one or more embodiments, the erase control unit applies voltages to the well to erase the memory cells in a manner that avoids breaking down p-n junctions formed by transistors fabricated in the well. In another embodiment, high voltage transistors are used to selectively isolate the bit lines from and couple the bit lines to a peripheral circuit in pairs so that each high voltage transistor is shared by two bit lines.
    Type: Grant
    Filed: January 10, 2008
    Date of Patent: August 16, 2011
    Assignee: Micron Technology, Inc.
    Inventors: Shigekazu Yamada, Tomoharu Tanaka
  • Publication number: 20110164456
    Abstract: Methods for programming a memory array and memory devices are disclosed. In one such method, inhibited bit lines are charged to an inhibit voltage that is less than a supply voltage. The word lines of memory cells to be programmed are biased at a programming preparation voltage that is less than a nominal programming preparation voltage as used in the conventional art. Programming pulses can be applied to selected word lines of the memory cells to be programmed when the uninhibited bit lines are at 0V.
    Type: Application
    Filed: March 18, 2011
    Publication date: July 7, 2011
    Inventor: Shigekazu Yamada
  • Publication number: 20110110163
    Abstract: A word line driver system that utilizes a voltage selection circuit to supply one of several voltages to an output node coupled to a plurality of word line control circuits. Each word line control circuit is coupled to a respective word line in an array of non-volatile memory cells. The voltage selection circuit may include selectable low pass filters for filtering the supplied voltage supplied to the word lines in the array of memory cells without significantly increasing the overall die-size of the device.
    Type: Application
    Filed: January 14, 2011
    Publication date: May 12, 2011
    Applicant: Micron Technology, Inc.
    Inventor: Shigekazu Yamada
  • Patent number: 7920428
    Abstract: Methods and apparatuses for automatically measuring memory cell threshold voltages are disclosed. Measurement circuitry includes an internal reference current generator, a plurality of memory cells and a bit line pre-charge reference circuit. If the reference current is greater than the memory cell current, the bit line voltage will increase. Conversely, if the reference current is less than the memory cell current, the bit line voltage will decrease. The reference current is generated in large steps until a comparator, that compares the bit line voltage and a bit line pre-charge reference voltage, is switched. The reference current then generates a current in small steps until the comparator is again switched. The reference current converges on the memory cell current within an accuracy of 10 nA. The memory cell threshold voltage is then determined from the memory cell current. Systems including memory according to an embodiment of the invention are also disclosed.
    Type: Grant
    Filed: January 12, 2009
    Date of Patent: April 5, 2011
    Assignee: Micron Technology, Inc.
    Inventor: Shigekazu Yamada
  • Patent number: 7916546
    Abstract: Methods for programming a memory array and memory devices are disclosed. In one such method, inhibited bit lines are charged to an inhibit voltage that is less than a supply voltage. The word lines of memory cells to be programmed are biased at a programming preparation voltage that is less than a nominal programming preparation voltage as used in the conventional art. Programming pulses can be applied to selected word lines of the memory cells to be programmed when the uninhibited bit lines are at 0V.
    Type: Grant
    Filed: April 27, 2009
    Date of Patent: March 29, 2011
    Assignee: Micron Technology, Inc.
    Inventor: Shigekazu Yamada
  • Patent number: 7916518
    Abstract: A memory device including current-limiting circuitry coupled to a first inverter inside a data register is provided. The current-limiting circuitry controls a voltage supplied to the first inverter and a reference voltage may be adjusted so that the voltage supplied to the first inverter is prevented from dropping below a voltage supplied to a second inverter inside the data register. The memory device may include a switch to allow coupling to the current-limiting circuitry for programming of the memory device.
    Type: Grant
    Filed: June 25, 2010
    Date of Patent: March 29, 2011
    Assignee: Intel Corporation
    Inventor: Shigekazu Yamada
  • Patent number: 7872920
    Abstract: A word line driver system that utilizes a voltage selection circuit to supply one of several voltages to an output node coupled to a plurality of word line control circuits. Each word line control circuit is coupled to a respective word line in an array of non-volatile memory cells. The voltage selection circuit may include selectable low pass filters for filtering the supplied voltage supplied to the word lines in the array of memory cells without significantly increasing the overall die-size of the device.
    Type: Grant
    Filed: October 2, 2009
    Date of Patent: January 18, 2011
    Assignee: Micron Technology, Inc.
    Inventor: Shigekazu Yamada
  • Publication number: 20100309730
    Abstract: Memory devices and erase methods for memories are disclosed, such as those adapted to discharge an erase voltage from a memory block while protecting low voltage string select gate transistors by maintaining the string select gate transistors in a turned on state during discharge.
    Type: Application
    Filed: June 3, 2009
    Publication date: December 9, 2010
    Inventors: Shigekazu Yamada, Tomoharu Tanaka
  • Publication number: 20100271871
    Abstract: Methods for programming a memory array and memory devices are disclosed. In one such method, inhibited bit lines are charged to an inhibit voltage that is less than a supply voltage. The word lines of memory cells to be programmed are biased at a programming preparation voltage that is less than a nominal programming preparation voltage as used in the conventional art. Programming pulses can be applied to selected word lines of the memory cells to be programmed when the uninhibited bit lines are at 0V.
    Type: Application
    Filed: April 27, 2009
    Publication date: October 28, 2010
    Inventor: Shigekazu Yamada
  • Publication number: 20100259977
    Abstract: A memory device including current-limiting circuitry coupled to a first inverter inside a data register is provided. The current-limiting circuitry controls a voltage supplied to the first inverter and a reference voltage may be adjusted so that the voltage supplied to the first inverter is prevented from dropping below a voltage supplied to a second inverter inside the data register. The memory device may include a switch to allow coupling to the current-limiting circuitry for programming of the memory device.
    Type: Application
    Filed: June 25, 2010
    Publication date: October 14, 2010
    Inventor: Shigekazu Yamada
  • Publication number: 20100246274
    Abstract: A semiconductor memory device is described that can, in certain embodiments, reduce a delay in access time and/or an area of a memory cell array. In one or more embodiments, a flash memory device that includes a memory cell array, a data register, a state machine, input/output pads, a row decoder, and a column decoder. The memory cell array includes a pre-charge unit that is placed between a plurality of memory cell arrays. The pre-charge unit pre-charges a bit line in a read operation. A data register is separated from the pre-charge unit and is located away from the arrays. Write data are coupled from a data register to the arrays, and read data are coupled from the arrays to the data register.
    Type: Application
    Filed: June 16, 2010
    Publication date: September 30, 2010
    Applicant: Micron Technology, Inc.
    Inventor: SHIGEKAZU YAMADA
  • Patent number: 7800953
    Abstract: A power supply circuit is used to supply power having a limited peak magnitude to an array of non-volatile memory cells during programming or erasing of the memory cells. The power supply circuit includes a reference current source supplying a reference current having a predetermined magnitude. The reference current source is coupled to a current generator, which supplies current to the array. The current generator may use current mirrors, and it supplies a current to the array having a predetermined relationship to the reference current. The current generator is selectively enabled by a control circuit so that current is supplied to the array during programming or erasing of at least some of the memory cells in the array.
    Type: Grant
    Filed: July 20, 2009
    Date of Patent: September 21, 2010
    Assignee: Micron Technology, Inc.
    Inventor: Shigekazu Yamada
  • Publication number: 20100220530
    Abstract: An integrated circuit bit line driver system includes a plurality of bit line drivers coupled to respective bit lines of an array of non-volatile memory cells. Each of the bit line drivers includes a bias transistor through which an input signal is coupled to the respective bit line. The bit line driver system includes a bias voltage circuit that generates a bias voltage that is coupled to the respective gates of the bias transistors. The bias voltage circuit initially accelerates the charging of the transistor gates, and subsequently completes charging the gates at a slower rate. The bias voltage is generated using a diode-coupled transistor having electrical characteristics the match those of the bias transistors so that the bias voltage varies with process or temperature variations of the integrated circuit in the same manner as the threshold voltage of the bias transistors vary with process or temperature variations.
    Type: Application
    Filed: May 14, 2010
    Publication date: September 2, 2010
    Applicant: Micron Technology, Inc.
    Inventor: Shigekazu Yamada
  • Patent number: 7768817
    Abstract: A memory device including current-limiting circuitry coupled to a first inverter inside a data register is provided. The current-limiting circuitry controls a voltage supplied to the first inverter and a reference voltage may be adjusted so that the voltage supplied to the first inverter is prevented from dropping below a voltage supplied to a second inverter inside the data register. The memory device may include a switch to allow coupling to the current-limiting circuitry for programming of the memory device.
    Type: Grant
    Filed: March 20, 2008
    Date of Patent: August 3, 2010
    Assignee: Intel Corporation
    Inventor: Shigekazu Yamada