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).
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Patent number: 8351247Abstract: 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: GrantFiled: February 17, 2010Date of Patent: January 8, 2013Assignee: Fujitsu Semiconductor LimitedInventors: Hiroyuki Ogawa, Hiroyoshi Tomita, Masato Takita
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Patent number: 8350310Abstract: 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: GrantFiled: May 16, 2012Date of Patent: January 8, 2013Assignee: Fujitsu Semiconductor LimitedInventors: Hiroyuki Ogawa, Hiroyoshi Tomita, Masato Takita
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Publication number: 20120225531Abstract: 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: ApplicationFiled: May 16, 2012Publication date: September 6, 2012Applicant: FUJITSU SEMICONDUCTOR LIMITEDInventors: Hiroyuki Ogawa, Hiroyoshi Tomita, Masato Takita
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Publication number: 20100321983Abstract: 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: ApplicationFiled: March 5, 2010Publication date: December 23, 2010Applicant: FUJITSU MICROELECTRONICS LIMITEDInventors: Masato Takita, Masato Matsumiya, Satoshi Eto, Toshikazu Nakamura, Masatomo Hasegawa, Ayako Kitamoto, Kuninori Kawabata, Hideki Kanou, Toru Koga, Yuki Ishii, Shinichi Yamada, Kaoru Mori
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Publication number: 20100220540Abstract: 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: ApplicationFiled: March 5, 2010Publication date: September 2, 2010Applicant: FUJISU MICROELECTRONICS LIMITEDInventors: Masato Takita, Masato Matsumiya, Satoshi Eto, Toshikazu Nakamura, Masatomo Hasegawa, Ayako Kitamoto, Kuninori Kawabata, Hideki Kanou, Toru Koga, Yuki Ishii, Shinichi Yamada, Kaoru Mori
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Publication number: 20100214823Abstract: 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: ApplicationFiled: February 17, 2010Publication date: August 26, 2010Applicant: FUJITSU MICROELECTRONICS LIMITEDInventors: Hiroyuki Ogawa, Hiroyoshi Tomita, Masato Takita
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Patent number: 7706209Abstract: 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: GrantFiled: December 22, 2005Date of Patent: April 27, 2010Assignee: Fujitsu Microelectronics LimitedInventors: Masato Takita, Masato Matsumiya, Satoshi Eto, Toshikazu Nakamura, Masatomo Hasegawa, Ayako Kitamoto, Kuninori Kawabata, Hideki Kanou, Toru Koga, Yuki Ishii, Shinichi Yamada, Kaoru Mori
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Patent number: 7187604Abstract: 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: GrantFiled: December 2, 2005Date of Patent: March 6, 2007Assignee: Fujitsu LimitedInventor: Masato Takita
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Patent number: 7079443Abstract: 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: GrantFiled: August 1, 2003Date of Patent: July 18, 2006Assignee: Fujitsu LimitedInventors: Masato Takita, Masato Matsumiya, Satoshi Eto, Toshikazu Nakamura, Masatomo Hasegawa, Ayako Kitamoto, Kuninori Kawabata, Hideki Kanou, Toru Koga, Yuki Ishii, Shinichi Yamada, Kaoru Mori
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Publication number: 20060098523Abstract: 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: ApplicationFiled: December 22, 2005Publication date: May 11, 2006Inventors: Masato Takita, Masato Matsumiya, Satoshi Eto, Toshikazu Nakamura, Masatomo Hasegawa, Ayako Kitamoto, Kuninori Kawabata, Hideki Kanou, Toru Koga, Yuki Ishii, Shinichi Yamada, Kaoru Mori
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Publication number: 20060098504Abstract: 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: ApplicationFiled: December 2, 2005Publication date: May 11, 2006Inventor: Masato Takita
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Patent number: 6992944Abstract: 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: GrantFiled: March 15, 2005Date of Patent: January 31, 2006Assignee: Fujitsu LimitedInventors: Masato Takita, Kuninori Kawabata
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Publication number: 20050157582Abstract: 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: ApplicationFiled: March 15, 2005Publication date: July 21, 2005Inventors: Masato Takita, Kuninori Kawabata
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Patent number: 6868023Abstract: 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: GrantFiled: September 8, 2003Date of Patent: March 15, 2005Assignee: Fujitsu LimitedInventors: Masato Takita, Shinichi Yamada, Masato Matsumiya
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Patent number: 6791354Abstract: 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: GrantFiled: January 2, 2002Date of Patent: September 14, 2004Assignee: Fujitsu LimitedInventors: Kaoru Mori, Shinichi Yamada, Masato Takita
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Publication number: 20040062088Abstract: 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: ApplicationFiled: September 8, 2003Publication date: April 1, 2004Applicant: FUJITSU LIMITEDInventors: Masato Takita, Shinichi Yamada, Masato Matsumiya
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Publication number: 20040022091Abstract: 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: ApplicationFiled: August 1, 2003Publication date: February 5, 2004Applicant: FUJITSU LIMITEDInventors: Masato Takita, Masato Matsumiya, Satoshi Eto, Toshikazu Nakamura, Masatomo Hasegawa, Ayako Kitamoto, Kuninori Kawabata, Hideki Kanou, Toru Koga, Yuki Ishii, Shinichi Yamada, Kaoru Mori
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Publication number: 20040013023Abstract: 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: ApplicationFiled: January 2, 2002Publication date: January 22, 2004Applicant: Fujitsu LimitedInventors: Kaoru Mori, Shinichi Yamada, Masato Takita
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Patent number: 6628564Abstract: 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: GrantFiled: June 25, 1999Date of Patent: September 30, 2003Assignee: Fujitsu LimitedInventors: Masato Takita, Masato Matsumiya, Satoshi Eto, Toshikazu Nakamura, Masatomo Hasegawa, Ayako Kitamoto, Kuninori Kawabata, Hideki Kanou, Toru Koga, Yuki Ishii, Shinichi Yamada, Kaoru Mori
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Patent number: 6605963Abstract: 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: GrantFiled: October 5, 1999Date of Patent: August 12, 2003Assignee: Fujitsu LimitedInventors: Ayako Kitamoto, Masato Matsumiya, Satoshi Eto, Masato Takita, Toshikazu Nakamura, Hideki Kanou, Kuninori Kawabata, Masatomo Hasegawa, Toru Koga, Yuki Ishii