Patents by Inventor Masato Takita

Masato Takita 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: 8351247
    Abstract: A semiconductor device includes a semiconductor substrate; a memory cell array including a plurality of memory cells formed on the semiconductor substrate and arranged in a matrix in a first direction and a second direction on the surface of the semiconductor substrate; a plurality of sense amplifiers formed on the semiconductor substrate and including a first sense amplifier and a second sense amplifier; and a plurality of bit lines extending along the first direction above the memory cell array, and arranged side by side in the second direction, wherein the plurality of bit lines include a first bit line pair formed in a first wiring layer and a second bit line pair formed in a second wiring layer located above the first wiring layer.
    Type: Grant
    Filed: February 17, 2010
    Date of Patent: January 8, 2013
    Assignee: Fujitsu Semiconductor Limited
    Inventors: Hiroyuki Ogawa, Hiroyoshi Tomita, Masato Takita
  • Patent number: 8350310
    Abstract: A semiconductor device includes a semiconductor substrate; a memory cell array including a plurality of memory cells formed on the semiconductor substrate and arranged in a matrix in a first direction and a second direction on the surface of the semiconductor substrate; a plurality of sense amplifiers formed on the semiconductor substrate and including a first sense amplifier and a second sense amplifier; and a plurality of bit lines extending along the first direction above the memory cell array, and arranged side by side in the second direction, wherein the plurality of bit lines include a first bit line pair formed in a first wiring layer and a second bit line pair formed in a second wiring layer located above the first wiring layer.
    Type: Grant
    Filed: May 16, 2012
    Date of Patent: January 8, 2013
    Assignee: Fujitsu Semiconductor Limited
    Inventors: Hiroyuki Ogawa, Hiroyoshi Tomita, Masato Takita
  • Publication number: 20120225531
    Abstract: A semiconductor device includes a semiconductor substrate; a memory cell array including a plurality of memory cells formed on the semiconductor substrate and arranged in a matrix in a first direction and a second direction on the surface of the semiconductor substrate; a plurality of sense amplifiers formed on the semiconductor substrate and including a first sense amplifier and a second sense amplifier; and a plurality of bit lines extending along the first direction above the memory cell array, and arranged side by side in the second direction, wherein the plurality of bit lines include a first bit line pair formed in a first wiring layer and a second bit line pair formed in a second wiring layer located above the first wiring layer.
    Type: Application
    Filed: May 16, 2012
    Publication date: September 6, 2012
    Applicant: FUJITSU SEMICONDUCTOR LIMITED
    Inventors: Hiroyuki Ogawa, Hiroyoshi Tomita, Masato Takita
  • Publication number: 20100321983
    Abstract: A semiconductor device includes a word line drive circuit for resetting the word line by driving the word line connected to a memory cell and is constituted so as to switch a reset level of the word line drive circuit, which is set at the time of the reset operation of the word line, between a first potential such as a ground potential and a second potential such as a negative potential. Further, a semiconductor device including a memory cell array formed by arranging a plurality of memory cells and a word line reset level generating circuit for generating a negative potential makes it possible to vary the amount of a current supply of the word line reset level generating circuit when non-selected word lines are set to a negative potential by applying the output of the word line reset level generating circuit to the non-selected word lines, and varies the amount of the current supply of the negative potential in accordance with the operation of the memory cell array.
    Type: Application
    Filed: March 5, 2010
    Publication date: December 23, 2010
    Applicant: FUJITSU MICROELECTRONICS LIMITED
    Inventors: Masato Takita, Masato Matsumiya, Satoshi Eto, Toshikazu Nakamura, Masatomo Hasegawa, Ayako Kitamoto, Kuninori Kawabata, Hideki Kanou, Toru Koga, Yuki Ishii, Shinichi Yamada, Kaoru Mori
  • Publication number: 20100220540
    Abstract: A semiconductor device includes a word line drive circuit for resetting the word line by driving the word line connected to a memory cell and is constituted so as to switch a reset level of the word line drive circuit, which is set at the time of the reset operation of the word line, between a first potential such as a ground potential and a second potential such as a negative potential. Further, a semiconductor device including a memory cell array formed by arranging a plurality of memory cells and a word line reset level generating circuit for generating a negative potential makes it possible to vary the amount of a current supply of the word line reset level generating circuit when non-selected word lines are set to a negative potential by applying the output of the word line reset level generating circuit to the non-selected word lines, and varies the amount of the current supply of the negative potential in accordance with the operation of the memory cell array.
    Type: Application
    Filed: March 5, 2010
    Publication date: September 2, 2010
    Applicant: FUJISU MICROELECTRONICS LIMITED
    Inventors: Masato Takita, Masato Matsumiya, Satoshi Eto, Toshikazu Nakamura, Masatomo Hasegawa, Ayako Kitamoto, Kuninori Kawabata, Hideki Kanou, Toru Koga, Yuki Ishii, Shinichi Yamada, Kaoru Mori
  • Publication number: 20100214823
    Abstract: A semiconductor device includes a semiconductor substrate; a memory cell array including a plurality of memory cells formed on the semiconductor substrate and arranged in a matrix in a first direction and a second direction on the surface of the semiconductor substrate; a plurality of sense amplifiers formed on the semiconductor substrate and including a first sense amplifier and a second sense amplifier; and a plurality of bit lines extending along the first direction above the memory cell array, and arranged side by side in the second direction, wherein the plurality of bit lines include a first bit line pair formed in a first wiring layer and a second bit line pair formed in a second wiring layer located above the first wiring layer.
    Type: Application
    Filed: February 17, 2010
    Publication date: August 26, 2010
    Applicant: FUJITSU MICROELECTRONICS LIMITED
    Inventors: Hiroyuki Ogawa, Hiroyoshi Tomita, Masato Takita
  • Patent number: 7706209
    Abstract: A semiconductor device, including a word line driver for driving a word line connected to a memory cell in a memory cell array and for resetting the word line when the memory cell changes from an activated to a standby state. The reset level of the word line driver is set when resetting of the word line is performed, and may be switched between first and second potentials. A word line reset level generating circuit varies the amount of negative potential current supply in accordance with memory cell array operating conditions. The semiconductor device includes a plurality of power source circuits, each having an oscillation circuit and a capacitor, for driving the capacitor via an oscillation signal outputted by the oscillation circuit. At least some power source circuits share a common oscillation circuit, and different capacitors are driven via the common oscillation signal.
    Type: Grant
    Filed: December 22, 2005
    Date of Patent: April 27, 2010
    Assignee: Fujitsu Microelectronics Limited
    Inventors: Masato Takita, Masato Matsumiya, Satoshi Eto, Toshikazu Nakamura, Masatomo Hasegawa, Ayako Kitamoto, Kuninori Kawabata, Hideki Kanou, Toru Koga, Yuki Ishii, Shinichi Yamada, Kaoru Mori
  • Patent number: 7187604
    Abstract: A shift register includes plural latches corresponding to normal word lines of normal memory cell rows and a redundancy word line of a redundancy memory cell row, respectively, in order to sequentially activate any of the redundancy word line and the normal word lines upon every refresh request. An activation circuit activates any of the normal word lines and redundancy word line according to an output of the shift register. A first storing circuit stores in advance a defect address indicating a defective normal memory cell row. A first activation control circuit prohibits activation of a normal word line corresponding to the defect address stored in the first storing circuit when the output of the shift register indicates the normal word line.
    Type: Grant
    Filed: December 2, 2005
    Date of Patent: March 6, 2007
    Assignee: Fujitsu Limited
    Inventor: Masato Takita
  • Patent number: 7079443
    Abstract: A semiconductor device includes a word line drive circuit for resetting the word line by driving the word line connected to a memory cell and is constituted so as to switch a reset level of the word line drive circuit, which is set at the time of the reset operation of the word line, between a first potential such as a ground potential and a second potential such as a negative potential. Further, a semiconductor device including a memory cell array formed by arranging a plurality of memory cells and a word line reset level generating circuit for generating a negative potential makes it possible to vary the amount of a current supply of the word line reset level generating circuit when non-selected word lines are set to a negative potential by applying the output of the word line reset level generating circuit to the non-selected word lines, and varies the amount of the current supply of the negative potential in accordance with the operation of the memory cell array.
    Type: Grant
    Filed: August 1, 2003
    Date of Patent: July 18, 2006
    Assignee: Fujitsu Limited
    Inventors: Masato Takita, Masato Matsumiya, Satoshi Eto, Toshikazu Nakamura, Masatomo Hasegawa, Ayako Kitamoto, Kuninori Kawabata, Hideki Kanou, Toru Koga, Yuki Ishii, Shinichi Yamada, Kaoru Mori
  • Publication number: 20060098523
    Abstract: A semiconductor device includes a word line drive circuit for resetting the word line by driving the word line connected to a memory cell and is constituted so as to switch a reset level of the word line drive circuit, which is set at the time of the reset operation of the word line, between a first potential such as a ground potential and a second potential such as a negative potential. Further, a semiconductor device including a memory cell array formed by arranging a plurality of memory cells and a word line reset level generating circuit for generating a negative potential makes it possible to vary the amount of a current supply of the word line reset level generating circuit when non-selected word lines are set to a negative potential by applying the output of the word line reset level generating circuit to the non-selected word lines, and varies the amount of the current supply of the negative potential in accordance with the operation of the memory cell array.
    Type: Application
    Filed: December 22, 2005
    Publication date: May 11, 2006
    Inventors: Masato Takita, Masato Matsumiya, Satoshi Eto, Toshikazu Nakamura, Masatomo Hasegawa, Ayako Kitamoto, Kuninori Kawabata, Hideki Kanou, Toru Koga, Yuki Ishii, Shinichi Yamada, Kaoru Mori
  • Publication number: 20060098504
    Abstract: A shift register includes plural latches corresponding to normal word lines of normal memory cell rows and a redundancy word line of a redundancy memory cell row, respectively, in order to sequentially activate any of the redundancy word line and the normal word lines upon every refresh request. An activation circuit activates any of the normal word lines and redundancy word line according to an output of the shift register. A first storing circuit stores in advance a defect address indicating a defective normal memory cell row. A first activation control circuit prohibits activation of a normal word line corresponding to the defect address stored in the first storing circuit when the output of the shift register indicates the normal word line.
    Type: Application
    Filed: December 2, 2005
    Publication date: May 11, 2006
    Inventor: Masato Takita
  • Patent number: 6992944
    Abstract: A semiconductor memory device includes a plurality of word decoders arranged in a plurality of columns, a plurality of word line selecting shift registers corresponding to the respective word decoders to indicate a word line subjected to refresh operation, and a shift control signal generating circuit operable to supply a shift control signal indicative of timing of shift operations to the plurality of word line selecting shift registers, wherein the said shift control signal generating circuit is configured to supply the shift control signal only to a column currently subjected to refresh operation among the plurality of columns.
    Type: Grant
    Filed: March 15, 2005
    Date of Patent: January 31, 2006
    Assignee: Fujitsu Limited
    Inventors: Masato Takita, Kuninori Kawabata
  • Publication number: 20050157582
    Abstract: A semiconductor memory device includes a plurality of word decoders arranged in a plurality of columns, a plurality of word line selecting shift registers corresponding to the respective word decoders to indicate a word line subjected to refresh operation, and a shift control signal generating circuit operable to supply a shift control signal indicative of timing of shift operations to the plurality of word line selecting shift registers, wherein the said shift control signal generating circuit is configured to supply the shift control signal only to a column currently subjected to refresh operation among the plurality of columns.
    Type: Application
    Filed: March 15, 2005
    Publication date: July 21, 2005
    Inventors: Masato Takita, Kuninori Kawabata
  • Patent number: 6868023
    Abstract: A semiconductor memory device includes a plurality of bit line pairs, each of which includes a first bit line and a second bit line, a plurality of memory cells which are coupled to said first bit line, and store electric charge in capacitors, a dummy cell which is coupled to a second bit line, and is charged with a predetermined potential, a sense amplifier which amplifies a potential difference between the first bit line and the second bit line, and a control circuit which charges said dummy cell with the predetermined potential only for a fixed time period.
    Type: Grant
    Filed: September 8, 2003
    Date of Patent: March 15, 2005
    Assignee: Fujitsu Limited
    Inventors: Masato Takita, Shinichi Yamada, Masato Matsumiya
  • Patent number: 6791354
    Abstract: A plurality of switching transistors is provided, each connects power supply terminals of a plurality of first circuit blocks to a power supply line, respectively. Among the first circuit blocks, the power supply terminals of the first circuit blocks operating at different timings are connected by an internal power supply line. A power supply control circuit simultaneously turns on the switching transistors connected to the internal power supply line, in response to operation(s) of at least any one of the first circuit blocks connected to the internal power supply line. Since the switching transistors can be shared among the first circuit blocks not operating simultaneously, operation speed of the first circuit blocks can be increased. Since a total size of the switching transistors can be made small, standby current can be decreased. Accordingly, a semiconductor integrated circuit operating at a high speed can be constituted without increasing the standby current.
    Type: Grant
    Filed: January 2, 2002
    Date of Patent: September 14, 2004
    Assignee: Fujitsu Limited
    Inventors: Kaoru Mori, Shinichi Yamada, Masato Takita
  • Publication number: 20040062088
    Abstract: A semiconductor memory device includes a plurality of bit line pairs, each of which includes a first bit line and a second bit line, a plurality of memory cells which are coupled to said first bit line, and store electric charge in capacitors, a dummy cell which is coupled to a second bit line, and is charged with a predetermined potential, a sense amplifier which amplifies a potential difference between the first bit line and the second bit line, and a control circuit which charges said dummy cell with the predetermined potential only for a fixed time period.
    Type: Application
    Filed: September 8, 2003
    Publication date: April 1, 2004
    Applicant: FUJITSU LIMITED
    Inventors: Masato Takita, Shinichi Yamada, Masato Matsumiya
  • Publication number: 20040022091
    Abstract: A semiconductor device includes a word line drive circuit for resetting the word line by driving the word line connected to a memory cell and is constituted so as to switch a reset level of the word line drive circuit, which is set at the time of the reset operation of the word line, between a first potential such as a ground potential and a second potential such as a negative potential. Further, a semiconductor device including a memory cell array formed by arranging a plurality of memory cells and a word line reset level generating circuit for generating a negative potential makes it possible to vary the amount of a current supply of the word line reset level generating circuit when non-selected word lines are set to a negative potential by applying the output of the word line reset level generating circuit to the non-selected word lines, and varies the amount of the current supply of the negative potential in accordance with the operation of the memory cell array.
    Type: Application
    Filed: August 1, 2003
    Publication date: February 5, 2004
    Applicant: FUJITSU LIMITED
    Inventors: Masato Takita, Masato Matsumiya, Satoshi Eto, Toshikazu Nakamura, Masatomo Hasegawa, Ayako Kitamoto, Kuninori Kawabata, Hideki Kanou, Toru Koga, Yuki Ishii, Shinichi Yamada, Kaoru Mori
  • Publication number: 20040013023
    Abstract: A plurality of switching transistors is provided, each connects power supply terminals of a plurality of first circuit blocks to a power supply line, respectively. Among the first circuit blocks, the power supply terminals of the first circuit blocks operating at different timings are connected by an internal power supply line. A power supply control circuit simultaneously turns on the switching transistors connected to the internal power supply line, in response to operation(s) of at least any one of the first circuit blocks connected to the internal power supply line. Since the switching transistors can be shared among the first circuit blocks not operating simultaneously, operation speed of the first circuit blocks can be increased. Since a total size of the switching transistors can be made small, standby current can be decreased. Accordingly, a semiconductor integrated circuit operating at a high speed can be constituted without increasing the standby current.
    Type: Application
    Filed: January 2, 2002
    Publication date: January 22, 2004
    Applicant: Fujitsu Limited
    Inventors: Kaoru Mori, Shinichi Yamada, Masato Takita
  • Patent number: 6628564
    Abstract: A semiconductor device includes a word line drive circuit resetting the word line by driving the word line connected to a memory cell and switching a reset level of the word line drive circuit at the time of the reset operation of the word line. Further, a semiconductor device includes a memory cell array formed by arranging a plurality of memory cells and a reset level switch circuit for selecting a first potential or a second potential and supplying the first potential or the second potential to the word line drive circuit.
    Type: Grant
    Filed: June 25, 1999
    Date of Patent: September 30, 2003
    Assignee: Fujitsu Limited
    Inventors: Masato Takita, Masato Matsumiya, Satoshi Eto, Toshikazu Nakamura, Masatomo Hasegawa, Ayako Kitamoto, Kuninori Kawabata, Hideki Kanou, Toru Koga, Yuki Ishii, Shinichi Yamada, Kaoru Mori
  • Patent number: 6605963
    Abstract: A semiconductor integrated circuit, comprising a circuit unit having a predetermined function such as a level shifter circuit or a driver transistor circuit by a combination of a plurality of transistors, is disclosed. Among a plurality of the transistors of the circuit unit, the source potential of at least one transistor adapted to turn off during the standby period of the circuit unit is changed. Preferably, the semiconductor integrated circuit is configured to reduce the sub-threshold current flowing between the source and the drain of at least one transistor adapted to turn off during the standby period of the circuit unit by changing the source potential at a timing based on the standby period of the circuit unit in such a manner that a predetermined bias voltage is applied between the gate and the source of the transistor. A method of switching the source potential of at least one transistor in the semiconductor integrated circuit having the configuration described above is also disclosed.
    Type: Grant
    Filed: October 5, 1999
    Date of Patent: August 12, 2003
    Assignee: Fujitsu Limited
    Inventors: Ayako Kitamoto, Masato Matsumiya, Satoshi Eto, Masato Takita, Toshikazu Nakamura, Hideki Kanou, Kuninori Kawabata, Masatomo Hasegawa, Toru Koga, Yuki Ishii