Patents by Inventor Yoshiyuki Katou

Yoshiyuki Katou 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: 7035154
    Abstract: The present invention provides a semiconductor memory device capable of checking operation in the worst case in address combinations, and its manufacturing method. Specific data for test are written into a memory cell array 30. Then, a test signal TE1 is set “1” to set a device in a test mode. Refresh addresses for test are then stored in a data store circuit 51. A first address for test is applied to an address terminal 21, whereby a normal read or write operation is accomplished based on the first address for test. A second address for test is applied to the address terminal 21, whereby a refresh operation is accomplished based on the address for test, and subsequently another normal read or write operation is accomplished based on the second address for test. Data of the memory cell array 30 are checked to decide the presence or absence of any abnormality.
    Type: Grant
    Filed: August 30, 2001
    Date of Patent: April 25, 2006
    Assignee: NEC Electronics Corporation
    Inventors: Hiroyuki Takahashi, Yoshiyuki Katou, Hideo Inaba, Shouzou Uchida, Masatoshi Sonoda
  • Patent number: 6944081
    Abstract: A semiconductor memory device capable of a further reduction in power consumption for refresh operation is provided. Cell arrays S0, S1 are divided into respective four blocks B0˜B3 and B10˜B13. In a normal read/write operation, by address data designating a word line, one of the cell arrays is selected, and also one block is selected in the selected cell array, and further one word line is selected in the selected block. In a refresh operation, one of the cell arrays is selected, and four blocks in the selected cell array are simultaneously refreshed. Namely, respective one word line is selected from each of the four blocks, and the selected word lines are refreshed, thereby to reduce a power comsumption as compared to when the plural cell arrays are refreshed.
    Type: Grant
    Filed: August 30, 2001
    Date of Patent: September 13, 2005
    Assignee: NEC Electronics Corporation
    Inventors: Hiroyuki Takahashi, Atsushi Nakagawa, Yoshiyuki Katou, Hideo Inaba, Noriaki Komatsu, Takuya Hirota, Masahiro Yoshida
  • Publication number: 20040041173
    Abstract: A semiconductor memory device capable of a further reduction in power consumption for refresh operation is provided. Cell arrays S0, S1 are divided into respective four blocks B0˜B3 and B10˜B13. In a normal read/write operation, by address data designating a word line, one of the cell arrays is selected, and also one block is selected in the selected cell array, and further one word line is selected in the selected block. In a refresh operation, one of the cell arrays is selected, and four blocks in the selected cell array are simultaneously refreshed. Namely, respective one word line is selected from each of the four blocks, and the selected word lines are refreshed, thereby to reduce a power comsumption as compared to when the plural cell arrays are refreshed.
    Type: Application
    Filed: August 13, 2003
    Publication date: March 4, 2004
    Inventors: Hiroyuki Takahashi, Atsushi Nakagawa, Yoshiyuki Katou, Hideo Inaba, Noriaki Komatsu, Takuya Hirota, Masahiro Yoshida
  • Publication number: 20040027898
    Abstract: The present invention provides a semiconductor memory device capable of checking operation in the worst case in address combinations, and its manufacturing method. Specific data for test are written into a memory cell array 30. Then, a test signal TE1 is set “1” to set a device in a test mode. Refresh addresses for test are then stored in a data store circuit 51. A first address for test is applied to an address terminal 21, whereby a normal read or write operation is accomplished based on the first address for test. A second address for test is applied to the address terminal 21, whereby a refresh operation is accomplished based on the address for test, and subsequently another normal read or write operation is accomplished based on the second address for test. Data of the memory cell array 30 are checked to decide the presence or absence of any abnormality.
    Type: Application
    Filed: August 21, 2003
    Publication date: February 12, 2004
    Inventors: Hiroyuki Takahashi, Yoshiyuki Katou, Hideo Inaba, Shouzou Uchida, Masatoshi Sonoda