Patents by Inventor Hiroyoshi Tsuboi

Hiroyoshi Tsuboi 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: 6971052
    Abstract: When a test command is received n times, any one of a plurality of tests is started. After the first test is started, any one of the tests is started or terminated every time the test command is received a predetermined number of times which is less than the n times. The number of times of the test command supplied to start or terminate the second and subsequent tests can be less than that of the first test. Accordingly, the time of the second and subsequent tests can be shortened. Since the first test is started only when the test command is received n times, the test is not started accidentally due to noise or the like in normal operation. Namely, the test time can be shortened without decreasing the operation reliability of an integrated circuit. Particularly, when a plurality of tests is executed successively, great benefit can be obtained.
    Type: Grant
    Filed: September 27, 2002
    Date of Patent: November 29, 2005
    Assignee: Fujitsu Limited
    Inventors: Hiroyoshi Tsuboi, Shinya Fujioka
  • Patent number: 6774673
    Abstract: A first switch operates in accordance with a control signal and receives an input signal. A voltage conversion circuit converts the input signal having a voltage and transmitted via the first switch to an output signal having a different voltage, and outputs the signal. A second switch connects an output node thereof to a voltage line supplied with a voltage which the voltage conversion circuit should output in accordance with the input signal. Therefore, even the input signal's voltage falling outside the range in which the voltage conversion circuit normally operates, the voltage that the voltage conversion circuit should intrinsically output is supplied to the output node via the second switch. Thus, reliable conversion of the input signal voltage is achieved, resulting in secure operation of the level shifter even during a low power supply voltage. This also prevents malfunction of the semiconductor integrated circuit incorporating such level shifters.
    Type: Grant
    Filed: October 15, 2002
    Date of Patent: August 10, 2004
    Assignee: Fujitsu Limited
    Inventors: Hiroyoshi Tsuboi, Yoshiaki Okuyama
  • Patent number: 6643809
    Abstract: A semiconductor device which has a test mode for testing the semiconductor device, is provided with a circuit which generates a first signal based on dummy command signals which are input thereto a plurality of times, and generates a second signal which instructs entry to a corresponding test mode or an exit from a corresponding test mode based on an address signal and the first signal.
    Type: Grant
    Filed: January 19, 2001
    Date of Patent: November 4, 2003
    Assignee: Fujitsu Limited
    Inventors: Hiroyoshi Tsuboi, Shinya Fujioka
  • Publication number: 20030102885
    Abstract: When a test command is received n times, any one of a plurality of tests is started. After the first test is started, any one of the tests is started or terminated every time the test command is received a predetermined number of times which is less than the n times. The number of times of the test command supplied to start or terminate the second and subsequent tests can be less than that of the first test. Accordingly, the time of the second and subsequent tests can be shortened. Since the first test is started only when the test command is received n times, the test is not started accidentally due to noise or the like in normal operation. Namely, the test time can be shortened without decreasing the operation reliability of an integrated circuit. Particularly, when a plurality of tests is executed successively, great benefit can be obtained.
    Type: Application
    Filed: September 27, 2002
    Publication date: June 5, 2003
    Applicant: Fujitsu Limited
    Inventors: Hiroyoshi Tsuboi, Shinya Fujioka
  • Publication number: 20030098711
    Abstract: A first switch operates in accordance with a control signal and receives an input signal. A voltage conversion circuit converts the input signal having a voltage and transmitted via the first switch to an output signal having a different voltage, and outputs the signal. A second switch connects an output node thereof to a voltage line supplied with a voltage which the voltage conversion circuit should output in accordance with the input signal. Therefore, even the input signal's voltage falling outside the range in which the voltage conversion circuit normally operates, the voltage that the voltage conversion circuit should intrinsically output is supplied to the output node via the second switch. Thus, reliable conversion of the input signal voltage is achieved, resulting in secure operation of the level shifter even during a low power supply voltage. This also prevents malfunction of the semiconductor integrated circuit incorporating such level shifters.
    Type: Application
    Filed: October 15, 2002
    Publication date: May 29, 2003
    Applicant: FUJITSU LIMITED
    Inventors: Hiroyoshi Tsuboi, Yoshiaki Okuyama
  • Patent number: 6487137
    Abstract: A semiconductor memory device which includes at least two memory cell arrays, a sense amplifier shared by the memory cell arrays and at least two transfer gates connected respectively between each of the memory cell arrays and the sense amplifier. The semiconductor memory device further includes a first voltage supplier supplying a first voltage to the transfer gates, and a second voltage supplier supplying a second voltage to the transfer gates, with second voltage being higher than the first voltage.
    Type: Grant
    Filed: August 9, 2001
    Date of Patent: November 26, 2002
    Assignee: Fujitsu Limited
    Inventors: Hiroyoshi Tsuboi, Shinya Fujioka, Koichi Nishimura
  • Publication number: 20020024868
    Abstract: A semiconductor memory device is provided. The semiconductor memory device comprises at least two memory cell arrays, a sense amplifier shared by the memory cell arrays, at least two transfer gates connected respectively between each of the memory cell arrays and the sense amplifier, a first voltage supplier supplying a first voltage to the transfer gates, and a second voltage supplier supplying a second voltage to the transfer gates. The second voltage is higher than the first voltage.
    Type: Application
    Filed: August 9, 2001
    Publication date: February 28, 2002
    Applicant: FUJITSU LIMITED
    Inventors: Hiroyoshi Tsuboi, Shinya Fujioka, Koichi Nishimura
  • Publication number: 20010017552
    Abstract: A semiconductor device which has a test mode for testing the semiconductor device, is provided with a circuit which generates a first signal based on dummy command signals which are input thereto a plurality of times, and generates a second signal which instructs entry to a corresponding test mode or an exit from a corresponding test mode based on an address signal and the first signal.
    Type: Application
    Filed: January 18, 2001
    Publication date: August 30, 2001
    Applicant: FUJITSU LIMITED
    Inventors: Hiroyoshi Tsuboi, Shinya Fujioka