Patents by Inventor Kotoku Sato

Kotoku Sato 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: 20030115405
    Abstract: A semiconductor memory device, such as a DRAM, which needs to be refreshed for retaining data, is provided with a storing portion for storing data therein, and a busy signal outputting portion outputting a busy signal during the refresh operation.
    Type: Application
    Filed: January 29, 2003
    Publication date: June 19, 2003
    Applicant: Fujitsu Limited
    Inventors: Akihiro Funyu, Shinya Fujioka, Hitoshi Ikeda, Takaaki Suzuki, Masao Taguchi, Kimiaki Satoh, Kotoku Sato, Yasurou Matsuzaki
  • Patent number: 6563746
    Abstract: An internal voltage generator when activated, generates an internal voltage to be supplied to an internal circuit. Operating the internal voltage generator consumes a predetermined amount of the power. In response to a control signal from the exterior, an entry circuit inactivates the internal voltage generator. When the internal voltage generator is inactivated, the internal voltage is not generated, thereby reducing the power consumption. By the control signal from the exterior, therefore, a chip can easily enter a low power consumption mode. The internal voltage generator is exemplified by a booster for generating the boost voltage of a word line connected with memory cells, a substrate voltage generator for generating a substrate voltage, or a precharging voltage generator for generating the precharging voltage of bit lines to be connected with the memory cells.
    Type: Grant
    Filed: March 30, 2001
    Date of Patent: May 13, 2003
    Assignee: Fujitsu Limited
    Inventors: Shinya Fujioka, Tomohiro Kawakubo, Koichi Nishimura, Kotoku Sato
  • Patent number: 6535965
    Abstract: A semiconductor memory device has a burst write mode in which predetermined plural command signals are input through a plurality of command pads and a mask control operation in the burst write mode is performed in response to the command signals. Therefore, the mask control in burst write mode is increased in speed to give an improved data transfer rate.
    Type: Grant
    Filed: April 27, 2000
    Date of Patent: March 18, 2003
    Assignee: Fujitsu Limited
    Inventors: Hitoshi Ikeda, Yasuharu Sato, Takaaki Suzuki, Toshiya Uchida, Kotoku Sato
  • Patent number: 6535950
    Abstract: A semiconductor memory device, such as a DRAM, which needs to be refreshed for retaining data, is provided with a storing portion for storing data therein, and a busy signal outputting portion outputting a busy signal during the refresh operation.
    Type: Grant
    Filed: March 29, 2000
    Date of Patent: March 18, 2003
    Assignee: Fujitsu Limited
    Inventors: Akihiro Funyu, Shinya Fujioka, Hitoshi Ikeda, Takaaki Suzuki, Masao Taguchi, Kimiaki Satoh, Kotoku Sato, Yasurou Matsuzaki
  • Patent number: 6515928
    Abstract: A semiconductor memory device that decreases power consumption and increases performance. The semiconductor memory device includes a plurality of memory cells that undergo refreshing to maintain data. The semiconductor memory device includes a normal operation mode for performing normal operation with the memory cells, and a plurality of low power consumption modes for decreasing power consumption when the semiconductor memory device is in a standby state. The semiconductor memory device includes a mode setting circuit that sets one of the low power consumption modes.
    Type: Grant
    Filed: August 28, 2001
    Date of Patent: February 4, 2003
    Assignee: Fujitsu Limited
    Inventors: Hajime Sato, Kotoku Sato, Satoru Kawamoto
  • Publication number: 20020064079
    Abstract: A semiconductor memory device that decreases power consumption and increases performance. The semiconductor memory device includes a plurality of memory cells that undergo refreshing to maintain data. The semiconductor memory device includes a normal operation mode for performing normal operation with the memory cells, and a plurality of low power consumption modes for decreasing power consumption when the semiconductor memory device is in a standby state. The semiconductor memory device includes a mode setting circuit that sets one of the low power consumption modes.
    Type: Application
    Filed: August 28, 2001
    Publication date: May 30, 2002
    Applicant: Fujitsu Limited
    Inventors: Hajime Sato, Kotoku Sato, Satoru Kawamoto
  • Patent number: 6397312
    Abstract: A memory system having a simple configuration capable of high-speed data transmission is disclosed. Data is output from a controller or a memory in synchronism with a clock or a data strobe signal. The clock or the data strobe signal is transmitted by a clock signal line or a data strobe signal line, respectively, arranged in parallel to a data signal line. A delay circuit delays by a predetermined time the signals transmitted through the clock signal line or the data strobe signal line. The clock or the data strobe signal thus assumes a phase suitable for retrieval at the destination, so that the data signal can be retrieved directly by means of the received clock or the received data strobe signal.
    Type: Grant
    Filed: November 13, 1997
    Date of Patent: May 28, 2002
    Assignee: Fujitsu Limited
    Inventors: Masao Nakano, Hiroyoshi Tomita, Kotoku Sato, Yoshihiro Takemae, Masao Taguchi
  • Publication number: 20020009012
    Abstract: An internal voltage generator when activated, generates an internal voltage to be supplied to an internal circuit. Operating the internal voltage generator consumes a predetermined amount of the power. In response to a control signal from the exterior, an entry circuit inactivates the internal voltage generator. When the internal voltage generator is inactivated, the internal voltage is not generated, thereby reducing the power consumption. By the control signal from the exterior, therefore, a chip can easily enter a low power consumption mode. The internal voltage generator is exemplified by a booster for generating the boost voltage of a word line connected with memory cells, a substrate voltage generator for generating a substrate voltage, or a precharging voltage generator for generating the precharging voltage of bit lines to be connected with the memory cells.
    Type: Application
    Filed: September 12, 2001
    Publication date: January 24, 2002
    Applicant: Fujitsu Limited
    Inventors: Shinya Fujioka, Tomohiro Kawakubo, Koichi Nishimura, Kotoku Sato
  • Publication number: 20020006071
    Abstract: A semiconductor memory device includes an SRAM provided on a chip, the SRAM including an SRAM cell array. A DRAM is provided on the chip, the DRAM including a DRAM cell array. An address input circuit receives an address signal, the address signal having a first portion and a second portion, the first portion carrying a unique value of row-column address information provided to access one of memory locations in one of the SRAM and DRAM cell arrays, the second portion carrying a unique value of SRAM/DRAM address information provided to select one of the SRAM and the DRAM.
    Type: Application
    Filed: July 31, 2001
    Publication date: January 17, 2002
    Applicant: Fujitsu Limited
    Inventors: Hitoshi Ikeda, Akihiro Funyu, Shinya Fujioka, Takaaki Suzuki, Masao Taguchi, Kimiaki Satoh, Kotoku Sato
  • Publication number: 20010043493
    Abstract: An internal voltage generator when activated, generates an internal voltage to be supplied to an internal circuit. Operating the internal voltage generator consumes a predetermined amount of the power. In response to a control signal from the exterior, an entry circuit inactivates the internal voltage generator. When the internal voltage generator is inactivated, the internal voltage is not generated, thereby reducing the power consumption. By the control signal from the exterior, therefore, a chip can easily enter a low power consumption mode. The internal voltage generator is exemplified by a booster for generating the boost voltage of a word line connected with memory cells, a substrate voltage generator for generating a substrate voltage, or a precharging voltage generator for generating the precharging voltage of bit lines to be connected with the memory cells.
    Type: Application
    Filed: March 30, 2001
    Publication date: November 22, 2001
    Applicant: Fujitsu Limited
    Inventors: Shinya Fujioka, Tomohiro Kawakubo, Koichi Nishimura, Kotoku Sato
  • Patent number: 6292426
    Abstract: A semiconductor memory device includes an SRAM provided on a chip, the SRAM including an SRAM cell array. A DRAM is provided on the chip, the DRAM including a DRAM cell array. An address input circuit receives an address signal, the address signal having a first portion and a second portion, the first portion carrying a unique value of row-column address information provided to access one of memory locations in one of the SRAM and DRAM cell arrays, the second portion carrying a unique value of SRAM/DRAM address information provided to select one of the SRAM and the DRAM.
    Type: Grant
    Filed: March 21, 2000
    Date of Patent: September 18, 2001
    Assignee: Fujitsu Limited
    Inventors: Hitoshi Ikeda, Akihiro Funyu, Shinya Fujioka, Takaaki Suzuki, Masao Taguchi, Kimiaki Satoh, Kotoku Sato
  • Patent number: 6172938
    Abstract: An electronic instrument includes a memory device, clock lines through which complementary clock signals are transmitted to be used for synchronization of a data output operation and a data input operation for the memory device, and strobe signal lines through which a first output strobe signal, a second output strobe signal, a first input strobe signal and a second input strobe signal are transmitted to be used to settle output data from the memory device in the data output operation and to settle input data supplied to the memory device, the first and second output strobe signals being in complementary relation to each other, the first and second input strobe signals being in complementary relation to each other.
    Type: Grant
    Filed: June 23, 1999
    Date of Patent: January 9, 2001
    Assignee: Fujitsu Limited
    Inventors: Takaaki Suzuki, Masao Taguchi, Kotoku Sato
  • Patent number: 6144616
    Abstract: A semiconductor memory device operating in synchronism with a clock includes an address latch&comparator part latching a first address signal associated with a write command and comparing the first address signal with a second address signal associated with a read command. A write data buffer part holds a data signal associated with the write command. The data signal held in the write data buffer part is read as a data signal requested by the read command when the first and second address signals coincide with each other.
    Type: Grant
    Filed: October 29, 1999
    Date of Patent: November 7, 2000
    Assignee: Fujitsu Limited
    Inventors: Takaaki Suzuki, Kotoku Sato
  • Patent number: 5901101
    Abstract: In a semiconductor memory device operable in synchronism with a clock signal externally supplied thereto, there are provided a first part which detects a state of a predetermined signal after a given command is input to the semiconductor memory; and a second part which sets, on the basis of the state of the predetermined signal, the semiconductor memory device to a self-refresh mode in which a refresh operation is carried out without an external signal.
    Type: Grant
    Filed: August 28, 1997
    Date of Patent: May 4, 1999
    Assignee: Fujitsu Limited
    Inventors: Takaaki Suzuki, Masao Nakano, Hiroyoshi Tomita, Yasuharu Sato, Kotoku Sato, Nobutaka Taniguchi