Patents by Inventor Sadayuki Ohkuma

Sadayuki Ohkuma 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: 5497353
    Abstract: A multiport memory is provided which permits both random access and serial access. In order to reduce parasitic capacitance and improve operating speed, the serial input/output lines are each divided into two parts at their middle points. Sense amplifiers for the serial input/output lines are provided at upper and lower ends of the serial access memory elements to respectively amplify signals from the divided lines. Additional features are provided for improving both the serial and random operation. For example, during the serial read mode, the column selector for random access is simultaneously operated, and read data passing through the random access column selector is used as head data for the serial output operation to be delivered through the serial output circuit. Also, a serial selector can be controlled by a select signal formed by a Gray Code counter to improve operating speed.
    Type: Grant
    Filed: March 30, 1995
    Date of Patent: March 5, 1996
    Assignees: Hitachi, Ltd., Hitachi VLSI Engineering Corp.
    Inventors: Katsuyuki Sato, Miki Matsumoto, Sadayuki Ohkuma, Masahiro Ogata, Masahiro Yoshida
  • Patent number: 5436870
    Abstract: A multiport memory is provided which permits both random access and serial access. In order to reduce parasitic capacitance and improve operating speed, the serial input/output lines are each divided into two parts at their middle points. Sense amplifiers for the serial input/output lines are provided at upper and lower ends of the serial access memory elements to respectively amplify signals from the divided lines. Additional features are provided for improving both the serial and random operation. For example, during the serial read mode, the column selector for random access is simultaneously operated, and read data passing through the random access column selector is used as head data for the serial output operation to be delivered through the serial output circuit. Also, a serial selector can be controlled by a select signal formed by a Gray Code counter to improve operating speed.
    Type: Grant
    Filed: August 3, 1994
    Date of Patent: July 25, 1995
    Assignees: Hitachi, Ltd., VLSI Engineering Corp.
    Inventors: Katsuyuki Sato, Miki Matsumoto, Sadayuki Ohkuma, Masahiro Ogata, Masahiro Yoshida
  • Patent number: 5313423
    Abstract: A multiport memory is provided which permits both random access and serial access. In order to reduce parasitic capacitance and improve operating speed, the serial input/output lines are each divided into two parts at their middle points. Sense amplifiers for the serial input/output lines are provided at upper and lower ends of the serial access memory elements to respectively amplify signals from the divided lines. Additional features are provided for improving both the serial and random operation. For example, during the serial read mode, the column selector for random access is simultaneously operated, and read data passing through the random access column selector is used as head data for the serial output operation to be delivered through the serial output circuit. Also, a serial selector can be controlled by a select signal formed by a Gray Code counter to improve operating speed.
    Type: Grant
    Filed: September 3, 1991
    Date of Patent: May 17, 1994
    Assignees: Hitachi, Ltd., Hitachi VLSI Engineering Corp.
    Inventors: Katsuyuki Sato, Miki Matsumoto, Sadayuki Ohkuma, Masahiro Ogata, Masahiro Yoshida
  • Patent number: 5289428
    Abstract: A multiport memory is provided which permits both random access and serial access. In order to reduce parasitic capacitance and improve operating speed, the serial input/output lines are each divided into two parts at their middle points. Sense amplifiers for the serial input/output lines are provided at upper and lower ends of the serial access memory elements to respectively amplify signals from the divided lines. Additional features are provided for improving both the serial and random operation. For example, during the serial read mode, the column selector for random access is simultaneously operated, and read data passing through the random access column selector is used as head data for the serial output operation to be delivered through the serial output circuit. Also, a serial selector can be controlled by a select signal formed by a Gray Code counter to improve operating speed.
    Type: Grant
    Filed: November 6, 1992
    Date of Patent: February 22, 1994
    Assignee: Hitachi Ltd., and Hitachi VLSI Engineering Corp.
    Inventors: Katsuyuki Sato, Miki Matsumoto, Sadayuki Ohkuma, Masahiro Ogata, Masahiro Yoshida
  • Patent number: 5274594
    Abstract: A static RAM comprises: column select circuits for connecting a plurality of pairs of corresponding complementary data lines at a unit of each pair with common complementary data lines; and redundant circuits each composed of the complementary data line pair and the column select circuit corresponding to the unit. Load MOSFETs of the complementary data lines are arranged close to the column select circuits to inhibit the column selecting operations by a decoder circuit and turn off the load MOSFETs when fuse means is cut. An access to a defective address is detected by a redundant decoder stored with the defective address, when the fuse means is selectively cut, to select the column select circuits of the redundant circuit.
    Type: Grant
    Filed: February 25, 1992
    Date of Patent: December 28, 1993
    Assignee: Hitachi, Ltd.
    Inventors: Kazumasa Yanagisawa, Atsushi Hiraishi, Hideyuki Aoki, Satoshi Oguchi, Sadayuki Ohkuma
  • Patent number: 5115413
    Abstract: A multiport memory is provided which permits both random access and serial access. In order to reduce parasitic capacitance and improve operating speed, the serial input/output lines are each divided into two parts at their middle points. Sense amplifiers for the serial input/output lines are provided at upper and lower ends of the serial access memory elements to respectively amplify signals from the divided lines. Additional features are provided for improving both the serial and random operation. For example, during the serial read mode, the column selector for random access is simultaneously operated, and read data passing through the random access column selector is used as head data for the serial output operation to be delivered through the serial output circuit. Also, a serial selector can be controlled by a select signal formed by a Gray Code counter to improve operating speed.
    Type: Grant
    Filed: March 20, 1990
    Date of Patent: May 19, 1992
    Assignees: Hitachi, Ltd., Hitachi VLSI Engineering Corporation
    Inventors: Katsuyuki Sato, Miki Matsumoto, Sadayuki Ohkuma, Masahiro Ogata, Masahiro Yoshida