Patents by Inventor Takahiko Sasaki

Takahiko Sasaki 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: 20120243295
    Abstract: A nonvolatile semiconductor memory device comprises a memory cell array, a control circuit, a current limiting circuit and a current suppression circuit. The memory cell array has a first line, a second line, and a memory cell arranged therein, the memory cell being connected between the first line and the second line and including a variable resistance element. The control circuit is configured to apply, via the first line and the second line, a voltage required in operation of the memory cell. The current limiting circuit is connected to the first line and configured to limit a current flowing in the memory cell to a certain limit value. The current suppression circuit is configured connectable to the second line and configured to suppress a current flowing in the second line according to a kind of operation on the memory cell.
    Type: Application
    Filed: March 19, 2012
    Publication date: September 27, 2012
    Applicant: KABUSHIKI KAISHA TOSHIBA
    Inventor: Takahiko SASAKI
  • Patent number: 8270201
    Abstract: According to one embodiment, a semiconductor memory device comprises a memory cell array and a control circuit. The control circuit applies a certain potential difference to a selected one of the memory cells. The control circuit comprises a current mirror circuit, a reference current generating circuit, and a detecting circuit. The current mirror circuit produces a mirror current having a current value identical to that of a cell current flowing in the selected one of the memory cells. The reference current generating circuit produces a reference current, the reference current having a current value that differs from the current value of the mirror current by a certain current value. The detecting circuit detects transition of a resistance state of the selected one of the memory cells based on a magnitude relation of the mirror current and the reference current.
    Type: Grant
    Filed: September 20, 2010
    Date of Patent: September 18, 2012
    Assignee: Kabushiki Kaisha Toshiba
    Inventor: Takahiko Sasaki
  • Patent number: 8270247
    Abstract: According to one embodiment, a word line driving circuit includes a driver and a booster circuit. The driver drives a word line based on an output of an inverter. The booster circuit connects a boosting capacitor to a source side of a P-channel field effect transistor of the inverter to boost the potential of the word line.
    Type: Grant
    Filed: September 17, 2010
    Date of Patent: September 18, 2012
    Assignee: Kabushiki Kaisha Toshiba
    Inventor: Takahiko Sasaki
  • Patent number: 8264867
    Abstract: According to one embodiment, a nonvolatile semiconductor storage device having a plurality of operation modes, includes: a plurality of first lines; a plurality of second lines; a plurality of memory cells; a first selection unit that charges the first line to a first selection voltage; and a second selection unit that charges a second line to an unselection voltage and discharges the second line to a second selection voltage after the first line is charged to the first selection voltage by the first selection unit, wherein the second selection unit adjusts at least one of a level of the second selection voltage to which the second line to be selected is to be discharged and a time constant when discharging the second line to be selected, in accordance with an operation mode in which the nonvolatile semiconductor storage device operates among the plurality of operation modes.
    Type: Grant
    Filed: September 20, 2010
    Date of Patent: September 11, 2012
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Kazuaki Kawaguchi, Takahiko Sasaki, Tomonori Kurosawa
  • Publication number: 20120224411
    Abstract: According to one embodiment, a control unit multiple-selects a first line for every N lines from a plurality of first lines. N is an integer greater than or equal to one. The control unit sets the multiple-selected first lines to a selection potential, and fixes potentials of non-selected first lines at least adjacent to the multiple-selected first lines at a first timing. The control unit causes the multiple-selected first lines to be in a floating state at a second timing after the first timing. The control unit selects one second line from the plurality of second lines and sets the one second line to a forming potential at a third timing after the second timing.
    Type: Application
    Filed: January 13, 2012
    Publication date: September 6, 2012
    Applicant: KABUSHIKI KAISHA TOSHIBA
    Inventors: Hiroshi KANNO, Takafumi Shimotori, Yoichi Minemura, Takahiko Sasaki, Takayuki Tsukamoto
  • Patent number: 8223579
    Abstract: A memory cell of a static random access memory (SRAM) includes a pair of drive transistors, a pair of load transistors, a pair of write-only transfer transistors, a pair of read-only transfer transistors, a pair of read-only drive transistors, and a pair of column selection transistors. The memory cell also includes a word line, a pair of write bit lines, a pair of read bit lines, and a column selection line.
    Type: Grant
    Filed: May 28, 2010
    Date of Patent: July 17, 2012
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Yasuhisa Takeyama, Osamu Hirabayashi, Takahiko Sasaki, Yuki Fujimura
  • Publication number: 20120149611
    Abstract: A coating composition for a sliding member, wherein from 30 to 120 parts by weight of a solid lubricant and from 5 to 80 parts by weight of a silicone resin are included per 100 parts by weight of a film-forming organic resin. As a result of forming the film on the surface of the sliding member, a coating composition for a sliding member is provided whereby low frictional drag can be maintained for an extended period of time, and the sticking of the sliding member to glass surfaces and similar smooth surfaces can be prevented.
    Type: Application
    Filed: August 19, 2010
    Publication date: June 14, 2012
    Inventors: Tetsuji Yamaguchi, Takahiko Sasaki
  • Patent number: 8149638
    Abstract: According to one embodiment, a semiconductor memory device includes a memory cell array includes memory cells, lines provided to correspond to the memory cells, a first decoder configured to select a first line as an inspection target from the lines, a second decoder configured to select a second line for generating a reference voltage from the lines, a driver configured to charge the first and second lines, a discharging circuit configured to simultaneously discharge the first and second lines, and a sense amplifier configured to compare a voltage of the first line with a voltage of the second line to detect a defect of the first line while the first line is discharged.
    Type: Grant
    Filed: September 17, 2010
    Date of Patent: April 3, 2012
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Tomonori Kurosawa, Takahiko Sasaki, Kazushige Kanda
  • Patent number: 8107278
    Abstract: A semiconductor storage device includes a memory cell array having a plurality of SRAM cells arranged along a pair of bit lines that extend along a first direction. A read circuit is arranged for each column at one side of the memory cell array and detects a potential of any one of the pair of bit lines. A write circuit is arranged, separately from the read circuit, at the other side of the memory cell array. The write circuit provides written data to the pair of bit lines to write data to the SRAM cells.
    Type: Grant
    Filed: December 4, 2008
    Date of Patent: January 31, 2012
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Takahiko Sasaki, Atsushi Kawasumi
  • Patent number: 8105886
    Abstract: A fuse link is formed between first and second terminals. The first and second terminals and fuse link have a polysilicon layer and a layer formed on the polysilicon layer and containing a metal element. At least a portion of the fuse link is an amorphous silicon layer.
    Type: Grant
    Filed: April 8, 2008
    Date of Patent: January 31, 2012
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Nobuaki Otsuka, Takahiko Sasaki, Shuso Fujii
  • Publication number: 20120014164
    Abstract: According to one embodiment, a resistance-change memory includes a memory element in which its variable resistance state corresponds to data to be stored therein, a pulse generation circuit which generates a first pulse, a second pulse, a third pulse, and a fourth pulse, the first pulse having a first amplitude which changes the resistance state of the memory element from a high- to a low-resistance state, the third pulse having a third amplitude smaller than the first amplitude to read data in the memory element, the fourth pulse having a fourth amplitude between the first amplitude and the third amplitude, and a control circuit which controls the operations of the memory element and the pulse generation circuit. The control circuit supplies the fourth pulse to the memory element after supplying the first pulse to the memory element.
    Type: Application
    Filed: July 13, 2011
    Publication date: January 19, 2012
    Inventors: Masahiro KAMOSHIDA, Katsuaki Sakurai, Takahiko Sasaki
  • Publication number: 20110255330
    Abstract: A nonvolatile semiconductor memory device according to one embodiment of the present invention includes a memory cell array configured by memory cells each provided between a first line and a second line and each including a variable resistor. A control circuit applies to any one of the memory cells through the first and second lines a voltage necessary for an operation of any one of the memory cells. A current limiting circuit is connected to the first line and limits a current flowing across the memory cell during an operation to a certain limit value. During an operation, the control circuit supplies a first voltage to the first line while supplying to the second line a second voltage. The second voltage lowers over time.
    Type: Application
    Filed: March 18, 2011
    Publication date: October 20, 2011
    Applicant: Kabushiki Kaisha Toshiba
    Inventors: Takahiko SASAKI, Tomonori Kurosawa
  • Publication number: 20110235394
    Abstract: A control circuit applies a first voltage to selected one of first lines and applies a second voltage having a voltage value smaller than that of the first voltage to selected one of second lines, such that a certain potential difference is applied across a memory cell disposed at an intersection of the selected one of the first lines and the selected one of the second lines. A current limiting circuit sets a compliance current defining an upper limit of a cell current flowing in the memory cell, and controls such that the cell current flowing in the memory cell does not exceed the compliance current. The current limiting circuit comprises a current generating circuit and a first current mirror circuit. The current generating circuit generates a first current having a current value equal to a current value of the cell current at a certain timing multiplied by a certain constant. The first current mirror circuit mirrors the first current to a current path supplying the first voltage to the first lines.
    Type: Application
    Filed: February 23, 2011
    Publication date: September 29, 2011
    Applicant: KABUSHIKI KAISHA TOSHIBA
    Inventors: Takahiko Sasaki, Tomonori Kurosawa
  • Publication number: 20110235397
    Abstract: A memory cell array includes a memory cell having a variable resistance element and disposed between first and second wirings. A control circuit provides a selected first wiring with a first voltage and provide a selected second wiring with a second voltage having a lower voltage value than the first voltage. A current limitation circuit controls a cell current below a first current. It includes a first current generation circuit for storing a cell current at a first point of time and generating a first current of ? times the stored cell current. It also includes a second current generation circuit for generating a second current of (?/?) times the cell current at a second point of time. A determination circuit outputs a control signal when the second current exceeds the stored current. The first current generation circuit newly stores a stored current according to the control signal.
    Type: Application
    Filed: March 18, 2011
    Publication date: September 29, 2011
    Applicant: Kabushiki Kaisha Toshiba
    Inventors: Takahiko SASAKI, Mizuki Uda
  • Publication number: 20110235399
    Abstract: A nonvolatile semiconductor memory device according to an embodiment includes a memory cell array configured by plural memory cells each including a variable resistor and each provided between first and second lines. A control circuit applies to a memory cell through the first and second lines a writing voltage for writing data or a reading voltage for reading data. A sense amplifier circuit senses data retained in a memory cell based on a current flowing through the first line. In a data writing operation, the control circuit applies a writing voltage to each of n number of memory cells configuring one unit such that the memory cells may be supplied with different resistance values. In a data reading operation, the sense amplifier circuit compares level relationship of the resistance values of n number of memory cells configuring one unit and reads out n! patterns of data from the one unit.
    Type: Application
    Filed: March 18, 2011
    Publication date: September 29, 2011
    Applicant: Kabushiki Kaisha Toshiba
    Inventor: Takahiko SASAKI
  • Publication number: 20110235392
    Abstract: According to one embodiment, a nonvolatile semiconductor storage device having a plurality of operation modes, includes: a plurality of first lines; a plurality of second lines; a plurality of memory cells; a first selection unit that charges the first line to a first selection voltage; and a second selection unit that charges a second line to an unselection voltage and discharges the second line to a second selection voltage after the first line is charged to the first selection voltage by the first selection unit, wherein the second selection unit adjusts at least one of a level of the second selection voltage to which the second line to be selected is to be discharged and a time constant when discharging the second line to be selected, in accordance with an operation mode in which the nonvolatile semiconductor storage device operates among the plurality of operation modes.
    Type: Application
    Filed: September 20, 2010
    Publication date: September 29, 2011
    Applicant: Kabushiki Kaisha Toshiba
    Inventors: Kazuaki KAWAGUCHI, Takahiko SASAKI, Tomonori KUROSAWA
  • Publication number: 20110235396
    Abstract: A semiconductor memory device includes a memory cell array, a first control circuit, and a second control circuit. The first control circuit is configured to apply a first voltage to a selected first line. The second control circuit is configured to apply a second voltage having a voltage value higher than that of the first voltage to a selected second line. The first control circuit includes a detecting circuit. The detecting circuit is configured to detect a leak current to flow from the second line to the first line through a memory cell during a forming operation for bringing the memory cell into a state that allows the memory cell to shift between a high resistance state and a low resistance state. The second control circuit includes a current supply circuit, and a compensating circuit. The current supply circuit is configured to supply a constant current to the second line during the forming operation.
    Type: Application
    Filed: March 18, 2011
    Publication date: September 29, 2011
    Applicant: Kabushiki Kaisha Toshiba
    Inventor: Takahiko SASAKI
  • Publication number: 20110222331
    Abstract: A semiconductor memory device in accordance with an embodiment includes: a memory cell array having memory cells disposed at respective intersections of first lines and second lines; and a control circuit configured to apply a first pulse voltage multiple times to selected one of the first lines and selected one of the second lines, such that a certain potential difference is applied to a selected memory cell thereby causing transition of a resistance state. The control circuit is configured to, when the selected memory cell is not caused to undergo transition of the resistance state even after application of the first pulse voltage a certain number of times, execute a rescue operation where a second pulse voltage is applied to the selected memory cell subsequent to application of the first pulse voltage, the second pulse voltage having a pulse width longer than that of the first pulse voltage.
    Type: Application
    Filed: March 9, 2011
    Publication date: September 15, 2011
    Applicant: KABUSHIKI KAISHA TOSHIBA
    Inventors: Tomonori KUROSAWA, Takahiko SASAKI
  • Publication number: 20110205779
    Abstract: According to one embodiment, a semiconductor storage device includes a memory cell array and a control circuit. The memory cell array has memory cells arranged therein at respective intersections between a plurality of first wirings and a plurality of second wirings. Each of the memory cells has a variable resistance element. The control circuit is configured to apply a voltage to a selected one of the first wirings and to a selected one of the second wirings. The control circuit includes a plurality of charge pump circuits and a plurality of clock oscillator circuits. The charge pump circuits generate a voltage applied to the first and second wirings. Each of the clock oscillator circuits is configured to supply a clock signal to a certain number of the charge pump circuits to control the timing of operation thereof. The clock oscillator circuits are configured to output clock signals at different frequencies.
    Type: Application
    Filed: June 18, 2010
    Publication date: August 25, 2011
    Applicant: KABUSHIKI KAISHA TOSHIBA
    Inventor: Takahiko SASAKI
  • Publication number: 20110199811
    Abstract: According to an embodiment, there are provided a non-volatile semiconductor memory device includes: a memory cell array; a control circuit performing a series of operations to each memory cell and determining, as a defective memory cell, a memory cell whose data retention property does not satisfy a criteria, the series of operations including an operation applying a first bias to the memory cell in a forward direction, and including an operation thereafter applying a second bias to the memory cell in a reverse direction; a storage unit storing an address of the defective memory cell; and an address control unit performing a control to avoid storing data in the defective memory cell whose address is stored in the storage unit.
    Type: Application
    Filed: September 17, 2010
    Publication date: August 18, 2011
    Applicant: Kabushiki Kaisha Toshiba
    Inventors: Hiroshi KANNO, Takayuki TSUKAMOTO, Takahiko SASAKI, Takafumi SHIMOTORI