Patents by Inventor Akihiro Funyu

Akihiro Funyu 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: 8111575
    Abstract: There is provided a semiconductor device including: a temperature sensor detecting temperature; an inner circuit operating when supplied with a power supply voltage from a power supply line; a switch connected between the power supply line and the inner circuit; and a control circuit performing control in which, in a case where the temperature detected by the temperature sensor is higher than a threshold value, the switch is turned on when the inner circuit is in operation and the switch is turned off when the inner circuit is in non-operation, and in a case where the temperature detected by the temperature sensor is lower than the threshold value, the switch is turned on when the inner circuit is in operation and in non-operation.
    Type: Grant
    Filed: January 8, 2010
    Date of Patent: February 7, 2012
    Assignee: Fujitsu Semiconductor Limited
    Inventors: Kaoru Mori, Shinya Fujioka, Yoshitaka Takahashi, Jun Ohno, Akihiro Funyu, Shinichiro Suzuki
  • Publication number: 20100110818
    Abstract: There is provided a semiconductor device including: a temperature sensor detecting temperature; an inner circuit operating when supplied with a power supply voltage from a power supply line; a switch connected between the power supply line and the inner circuit; and a control circuit performing control in which, in a case where the temperature detected by the temperature sensor is higher than a threshold value, the switch is turned on when the inner circuit is in operation and the switch is turned off when the inner circuit is in non-operation, and in a case where the temperature detected by the temperature sensor is lower than the threshold value, the switch is turned on when the inner circuit is in operation and in non-operation.
    Type: Application
    Filed: January 8, 2010
    Publication date: May 6, 2010
    Applicant: FUJITSU MICROELECTRONICS LIMITED
    Inventors: Kaoru MORI, Shinya Fujioka, Yoshitaka Takahashi, Jun Ohno, Akihiro Funyu, Shinichiro Suzuki
  • Patent number: 7471585
    Abstract: A refresh signal is output in response to a refresh request generated at predetermined cycles, and a refresh operation is performed. The refresh operation ends when a conflict occurs between an access request and the refresh request. Consequently, an access operation corresponding to the access request can be started earlier with a reduction in access time. The access time can be reduced further by changing the end time of the refresh operation in accordance with the timing of supply of the access request. Since a test circuit for notifying the state of the refresh operation to exterior is formed, the operation margin of the refresh operation can be evaluated in a short time. As a result, it is possible to reduce the development period of the semiconductor memory.
    Type: Grant
    Filed: August 24, 2006
    Date of Patent: December 30, 2008
    Assignee: Fujitsu Limited
    Inventors: Naoharu Shinozaki, Tatsuya Kanda, Takahiko Sato, Akihiro Funyu
  • Publication number: 20060285413
    Abstract: A refresh signal is output in response to a refresh request generated at predetermined cycles, and a refresh operation is performed. The refresh operation ends when a conflict occurs between an access request and the refresh request. Consequently, an access operation corresponding to the access request can be started earlier with a reduction in access time. The access time can be reduced further by changing the end time of the refresh operation in accordance with the timing of supply of the access request. Since a test circuit for notifying the state of the refresh operation to exterior is formed, the operation margin of the refresh operation can be evaluated in a short time. As a result, it is possible to reduce the development period of the semiconductor memory.
    Type: Application
    Filed: August 24, 2006
    Publication date: December 21, 2006
    Inventors: Naoharu Shinozaki, Tatsuya Kanda, Takahiko Sato, Akihiro Funyu
  • Patent number: 7114025
    Abstract: A semiconductor memory includes a refresh timer and an arbiter for determining the order of precedence between an access operation and a refresh operation, in order to automatically perform refresh operations inside the memory. A detecting circuit operates in a test mode and outputs a detection signal indicating that the refresh operation is yet to be performed, when a new internal refresh request occurs before the refresh operation is performed. For example, the detection signal is output when the interval of access requests is short and no refresh operation can be inserted between the access operations. That is, in the semiconductor memory in which refresh operations are performed automatically, it is possible to evaluate the minimum interval of supplying access requests. As a result, the evaluation time can be reduced with a reduction in the development period of the semiconductor memory.
    Type: Grant
    Filed: October 21, 2003
    Date of Patent: September 26, 2006
    Assignee: Fujitsu Limited
    Inventors: Tatsuya Kanda, Akihiro Funyu, Takahiko Sato, Yoshiaki Okuyama, Jun Ohno, Hitoshi Ikeda
  • Patent number: 7113441
    Abstract: A refresh signal is output in response to a refresh request generated at predetermined cycles, and a refresh operation is performed. The refresh operation ends when a conflict occurs between an access request and the refresh request. Consequently, an access operation corresponding to the access request can be started earlier with a reduction in access time. The access time can be reduced further by changing the end time of the refresh operation in accordance with the timing of supply of the access request. Since a test circuit for notifying the state of the refresh operation to exterior is formed, the operation margin of the refresh operation can be evaluated in a short time. As a result, it is possible to reduce the development period of the semiconductor memory.
    Type: Grant
    Filed: February 15, 2005
    Date of Patent: September 26, 2006
    Assignee: Fujitsu Limited
    Inventors: Naoharu Shinozaki, Tatsuya Kanda, Takahiko Sato, Akihiro Funyu
  • Publication number: 20050146968
    Abstract: A refresh signal is output in response to a refresh request generated at predetermined cycles, and a refresh operation is performed. The refresh operation ends when a conflict occurs between an access request and the refresh request. Consequently, an access operation corresponding to the access request can be started earlier with a reduction in access time. The access time can be reduced further by changing the end time of the refresh operation in accordance with the timing of supply of the access request. Since a test circuit for notifying the state of the refresh operation to exterior is formed, the operation margin of the refresh operation can be evaluated in a short time. As a result, it is possible to reduce the development period of the semiconductor memory.
    Type: Application
    Filed: February 15, 2005
    Publication date: July 7, 2005
    Inventors: Naoharu Shinozaki, Tatsuya Kanda, Takahiko Sato, Akihiro Funyu
  • Publication number: 20040199717
    Abstract: A semiconductor memory includes a refresh timer and an arbiter for determining the order of precedence between an access operation and a refresh operation, in order to automatically perform refresh operations inside the memory. A detecting circuit operates in a test mode and outputs a detection signal indicating that the refresh operation is yet to be performed, when a new internal refresh request occurs before the refresh operation is performed. For example, the detection signal is output when the interval of access requests is short and no refresh operation can be inserted between the access operations. That is, in the semiconductor memory in which refresh operations are performed automatically, it is possible to evaluate the minimum interval of supplying access requests. As a result, the evaluation time can be reduced with a reduction in the development period of the semiconductor memory.
    Type: Application
    Filed: October 21, 2003
    Publication date: October 7, 2004
    Applicant: FUJITSU LIMITED
    Inventors: Tatsuya Kanda, Akihiro Funyu, Takahiko Sato, Yoshiaki Okuyama, Jun Ohno, Hitoshi Ikeda
  • Patent number: 6735141
    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: July 31, 2001
    Date of Patent: May 11, 2004
    Assignee: Fujitsu Limited
    Inventors: Hitoshi Ikeda, Akihiro Funyu, Shinya Fujioka, Takaaki Suzuki, Masao Taguchi, Kimiaki Satoh, Kotoku Sato
  • Patent number: 6724675
    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: January 29, 2003
    Date of Patent: April 20, 2004
    Assignee: Fujitsu Limited
    Inventors: Akihiro Funyu, Shinya Fujioka, Hitoshi Ikeda, Takaaki Suzuki, Masao Taguchi, Kimiaki Satoh, Kotoku Sato, Yasurou Matsuzaki
  • 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: 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: 6496433
    Abstract: A semiconductor device has a normal mode and a test mode for testing the semiconductor device, and is provided with a first circuit which receives an input signal, a test signal and an output enable signal, and outputs the input signal in response to the output enable signal, a second circuit which is coupled to the first circuit and outputs the input signal obtained from the first circuit, and power supply pads which receive a power supply voltage which is supplied in common to the first circuit and the second circuit. The first circuit fixes an output impedance of the second circuit to a high-impedance regardless of the output enable signal when the test signal indicates the test mode.
    Type: Grant
    Filed: January 9, 2001
    Date of Patent: December 17, 2002
    Assignee: Fujitsu Limited
    Inventors: Yasuhiro Okumura, Yoshitaka Takahashi, Akihiro Funyu
  • Patent number: 6452453
    Abstract: The constant-current generator comprises a bias transistor whose drain and gate are connected to each other, and an outputting transistor. The threshold voltage of the outputting transistor is smaller than that of the bias transistor. The outputting transistor has the same source voltage and the same gate voltage as those of the bias transistor. Therefore, the gate-to-source voltages of the outputting transistor and the bias transistor are always kept equal. On the other hand, the drain-to-source current of the outputting transistor becomes larger than that of the bias transistor in accordance with the difference between the threshold voltages of the outputting transistor and the bias transistor. Accordingly, the outputting transistor can output a stable drain-to-source current even when the drain voltage of the bias transistor has shifted to lower the gate-to-source voltage thereof.
    Type: Grant
    Filed: May 1, 2000
    Date of Patent: September 17, 2002
    Assignee: Fujitsu Limited
    Inventors: Shinya Fujioka, Akihiro Funyu
  • Patent number: 6404688
    Abstract: A semiconductor memory device having a self-refresh operation includes a first circuit generating a first signal that specifies a first self-refresh cycle by a non-volatile circuit element provided in the semiconductor memory device, a second circuit receiving a second signal that specifies a second self-refresh cycle via a terminal that is used in common to another signal, and a third circuit generating a pulse signal having one of the first and second self-refresh cycles, the pulse signal being related to the self-refresh operation.
    Type: Grant
    Filed: February 26, 2001
    Date of Patent: June 11, 2002
    Assignee: Fujitsu Limited
    Inventors: Yoshiaki Okuyama, Yoshitaka Takahashi, Shinya Fujioka, Akihiro Funyu
  • Patent number: 6396758
    Abstract: A semiconductor memory device having a self-refresh operation includes a detection circuit generating a detection signal when detecting a change of a given input signal, and a comparator circuit comparing the detection signal with a refresh request signal internally generated and generating a control signal indicative of a circuit operation.
    Type: Grant
    Filed: February 27, 2001
    Date of Patent: May 28, 2002
    Assignee: Fujitsu Limited
    Inventors: Hitoshi Ikeda, Tatsuya Kanda, Yoshitaka Takahashi, Shinya Fujioka, Akihiro Funyu
  • Patent number: 6353561
    Abstract: A semiconductor memory device, such as a synchronous DRAM, receives external commands and an external clock signal via input buffers. The device generates internal clock signals having a slower frequency than the external clock signal and uses the internal clock signals to acquire the external command. This allows more than one external command to be acquired for each cycle of the external clock. The acquired external commands are provided to command decoders for decoding. A mask circuit is connected to the decoder circuits and inhibits the decoding circuits, except for a first one of the decoding circuits, from decoding the external commands for a predetermined time period, when the first decoder circuit is decoding the external commands.
    Type: Grant
    Filed: September 17, 1999
    Date of Patent: March 5, 2002
    Assignee: Fujitsu Limited
    Inventors: Akihiro Funyu, Shinya Fujioka, Yasuharu Sato, Toshiya Uchida
  • Publication number: 20020024847
    Abstract: A semiconductor device includes a plurality of word lines selectable in a predetermined mode, and a circuit that precharges the plurality of word lines selected in the predetermined mode in a time division manner.
    Type: Application
    Filed: August 15, 2001
    Publication date: February 28, 2002
    Applicant: FUJITSU LIMITED
    Inventors: Katsuhiro Mori, Shinya Fujioka, Akihiro Funyu
  • 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
  • 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