Patents by Inventor Akihito Tohata

Akihito Tohata 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: 7978562
    Abstract: A semiconductor memory device operates by using a fixed power and a variable power. The device includes a plurality of word lines which select rows of a memory cell array, a plurality of word line drivers each of which is connected to a corresponding one of the word lines and includes a first CMOS gate, a first cutoff switch which is connected between a fixed power terminal and a power terminal of the first CMOS gate and cuts off the fixed power in a sleep mode, a switching circuit which is connected to the plurality of word lines and connects the plurality of word lines to a ground terminal in the sleep mode, and a power control circuit which generates the variable power by using the fixed power and sets the variable power to 0 V in the sleep mode.
    Type: Grant
    Filed: September 28, 2009
    Date of Patent: July 12, 2011
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Tomoaki Yabe, Akihito Tohata
  • Patent number: 7791971
    Abstract: A semiconductor memory device includes first and second cell arrays which have memory cells arrayed in row and column directions, first and second bit lines which are connected to the memory cells arrayed in the column direction, and first and second sense amplifiers which are connected to the first, second bit lines, respectively. The device also includes first and second dummy cell arrays which have dummy cells arrayed in the row and column directions, a dummy word line which is connected to the dummy cells arrayed in the row direction, first and second dummy bit lines which are connected to the dummy cells arrayed in the column direction and receive an output from the dummy word line, and first and second sense amplifier activation circuits which activate the first, second sense amplifiers in accordance with first and second control signals output from the first and second dummy bit lines, respectively.
    Type: Grant
    Filed: April 27, 2009
    Date of Patent: September 7, 2010
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Akihito Tohata, Tomoaki Yabe
  • Publication number: 20100014375
    Abstract: A semiconductor memory device operates by using a fixed power and a variable power. The device includes a plurality of word lines which select rows of a memory cell array, a plurality of word line drivers each of which is connected to a corresponding one of the word lines and includes a first CMOS gate, a first cutoff switch which is connected between a fixed power terminal and a power terminal of the first CMOS gate and cuts off the fixed power in a sleep mode, a switching circuit which is connected to the plurality of word lines and connects the plurality of word lines to a ground terminal in the sleep mode, and a power control circuit which generates the variable power by using the fixed power and sets the variable power to 0 V in the sleep mode.
    Type: Application
    Filed: September 28, 2009
    Publication date: January 21, 2010
    Inventors: Tomoaki YABE, Akihito Tohata
  • Patent number: 7606106
    Abstract: A semiconductor memory device operates by using a fixed power and a variable power. The device includes a plurality of word lines which select rows of a memory cell array, a plurality of word line drivers each of which is connected to a corresponding one of the word lines and includes a first CMOS gate, a first cutoff switch which is connected between a fixed power terminal and a power terminal of the first CMOS gate and cuts off the fixed power in a sleep mode, a switching circuit which is connected to the plurality of word lines and connects the plurality of word lines to a ground terminal in the sleep mode, and a power control circuit which generates the variable power by using the fixed power and sets the variable power to 0 V in the sleep mode.
    Type: Grant
    Filed: September 13, 2007
    Date of Patent: October 20, 2009
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Tomoaki Yabe, Akihito Tohata
  • Publication number: 20090213635
    Abstract: A semiconductor memory device includes first and second cell arrays which have memory cells arrayed in row and column directions, first and second bit lines which are connected to the memory cells arrayed in the column direction, and first and second sense amplifiers which are connected to the first, second bit lines, respectively. The device also includes first and second dummy cell arrays which have dummy cells arrayed in the row and column directions, a dummy word line which is connected to the dummy cells arrayed in the row direction, first and second dummy bit lines which are connected to the dummy cells arrayed in the column direction and receive an output from the dummy word line, and first and second sense amplifier activation circuits which activate the first, second sense amplifiers in accordance with first and second control signals output from the first and second dummy bit lines, respectively.
    Type: Application
    Filed: April 27, 2009
    Publication date: August 27, 2009
    Applicant: KABUSHIKI KAISHA TOSHIBA
    Inventors: Akihito Tohata, Tomoaki Yabe
  • Patent number: 7535784
    Abstract: A semiconductor memory device includes first and second cell arrays which have memory cells arrayed in row and column directions, first and second bit lines which are connected to the memory cells arrayed in the column direction, and first and second sense amplifiers which are connected to the first, second bit lines, respectively. The device also includes first and second dummy cell arrays which have dummy cells arrayed in the row and column directions, a dummy word line which is connected to the dummy cells arrayed in the row direction, first and second dummy bit lines which are connected to the dummy cells arrayed in the column direction and receive an output from the dummy word line, and first and second sense amplifier activation circuits which activate the first, second sense amplifiers in accordance with first and second control signals output from the first and second dummy bit lines, respectively.
    Type: Grant
    Filed: October 15, 2007
    Date of Patent: May 19, 2009
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Akihito Tohata, Tomoaki Yabe
  • Publication number: 20090090973
    Abstract: A semiconductor device includes a device isolation insulating film which is provided in a semiconductor substrate, and an insulated-gate field-effect transistor which is disposed adjacent to the device isolation insulating film in a gate length direction, the insulated-gate field-effect transistor including a gate insulation film which is provided on the semiconductor substrate, a gate electrode which is provided on the gate insulation film, a pair of impurity diffusion layers which are provided spaced apart in the semiconductor substrate in a manner to sandwich the gate electrode, and a redundant impurity diffusion layer which is provided between the device isolation insulating film and one of the pair of impurity diffusion layers.
    Type: Application
    Filed: October 2, 2008
    Publication date: April 9, 2009
    Inventors: Akihito TOHATA, Osamu HIRABAYASHI
  • Publication number: 20080089156
    Abstract: A semiconductor memory device includes first and second cell arrays which have memory cells arrayed in row and column directions, first and second bit lines which are connected to the memory cells arrayed in the column direction, and first and second sense amplifiers which are connected to the first, second bit lines, respectively. The device also includes first and second dummy cell arrays which have dummy cells arrayed in the row and column directions, a dummy word line which is connected to the dummy cells arrayed in the row direction, first and second dummy bit lines which are connected to the dummy cells arrayed in the column direction and receive an output from the dummy word line, and first and second sense amplifier activation circuits which activate the first, second sense amplifiers in accordance with first and second control signals output from the first and second dummy bit lines, respectively.
    Type: Application
    Filed: October 15, 2007
    Publication date: April 17, 2008
    Applicant: KABUSHIKI KAISHA TOSHIBA
    Inventors: Akihito Tohata, Tomoaki Yabe
  • Publication number: 20080068915
    Abstract: A semiconductor memory device operates by using a fixed power and a variable power. The device includes a plurality of word lines which select rows of a memory cell array, a plurality of word line drivers each of which is connected to a corresponding one of the word lines and includes a first CMOS gate, a first cutoff switch which is connected between a fixed power terminal and a power terminal of the first CMOS gate and cuts off the fixed power in a sleep mode, a switching circuit which is connected to the plurality of word lines and connects the plurality of word lines to a ground terminal in the sleep mode, and a power control circuit which generates the variable power by using the fixed power and sets the variable power to 0 V in the sleep mode.
    Type: Application
    Filed: September 13, 2007
    Publication date: March 20, 2008
    Inventors: Tomoaki Yabe, Akihito Tohata