Patents by Inventor Sho Yamamoto

Sho Yamamoto 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: 5087956
    Abstract: An SRAM including a memory cell having a high-resistance load element. The load element is formed from a polysilicon film, and an impurity is introduced into at least a part of the polysilicon film for the purpose of increasing the threshold voltage of a parasitic MISFET formed using the load element as its channel region. Alternatively, the deposition of the polysilicon film is carried out at a relatively high temperature, thereby preventing any increase in the current flowing through the load element, and thus reducing the power dissipation in the SRAM.
    Type: Grant
    Filed: May 30, 1989
    Date of Patent: February 11, 1992
    Assignee: Hitachi, Ltd.
    Inventors: Shuji Ikeda, Satoshi Meguro, Kotaro Nishimura, Sho Yamamoto, Nobuyoshi Tanimura
  • Patent number: 4890148
    Abstract: A static RAM exhibiting a high reliability and suited to a higher density of integration is disclosed. In each memory cell of this static RAM, the cross coupling of a flip-flop circuit is made by gate electrodes of MISFETs constituting this flip-flop circuit. In addition, a source line is formed by the same step as that of a word line. A resistance value of a polycrystalline silicon layer which is a load resistor is changed in accordance with information to be stored. Furthermore, semiconductor regions for preventing soft errors attributed to alpha particles etc. are formed under the MISFETs constituting the flip-flop circuit, so that the channels are not adversely affected.
    Type: Grant
    Filed: July 7, 1988
    Date of Patent: December 26, 1989
    Assignee: Hitachi, Ltd.
    Inventors: Shuji Ikeda, Kouichi Nagasawa, Satoshi Meguro, Sho Yamamoto
  • Patent number: 4876669
    Abstract: An MOS static type RAM has a memory cell array comprising of a plurality of static type memory cells arranged in matrix, a plurality of data lines connected to the data input-output terminals of the respective memory cells and a plurality of word lines connected to the selection terminals of the respective memory cells. Data line load circuits are disposed between the power terminal of the circuit and the data lines. Each data line load circuit is kept at a relatively high impedance in the data write-in operation, and at a relatively low impedance in the data read-out operation. The use of the data line load circuits comprised of such variable impedance circuits can speed up the operating speed of the RAM and can accomplish lower power consumption.
    Type: Grant
    Filed: June 7, 1988
    Date of Patent: October 24, 1989
    Assignee: Hitachi Microcomputer Hitachi, Ltd. & Engineering, Ltd.
    Inventors: Sho Yamamoto, Osamu Minato, Makoto Saeki, Yasuo Yoshitomi, Hideaki Nakamura, Masaaki Kubotera
  • Patent number: 4841481
    Abstract: An SRAM including a memory cell having a high-resistance load element. The load element is formed from a polysilicon film, and an impurity is introduced into a least a part of the polysilicon film for the purpose of increasing the threshold voltage of a parasitic MISFET formed using the load element as its channel region. Alternatively, the deposition of the polysilicon film is carried out at a relatively high temperature, thereby preventing any increase in the current flowing through the load element, and thus reducing the power dissipation in the SRAM.
    Type: Grant
    Filed: July 28, 1988
    Date of Patent: June 20, 1989
    Assignee: Hitachi, Ltd.
    Inventors: Shuji Ikeda, Satoshi Meguro, Kotaro Nishimura, Sho Yamamoto, Nobuyoshi Tanimura
  • Patent number: 4774203
    Abstract: A method of making a static random-access memory device or SRAM including a memory cell having a high-resistance load element. The load element is formed from a polysilicon film, and an impurity is introduced into at least a part of the polysilicon film for the purpose of increasing the threshold voltage of a parasitic MISFET formed using the load element as its channel region. Alternatively, the deposition of the polysilicon film is carried out at a relatively high temperature, thereby preventing any increase in the current flowing through the load element, and thus reducing the power dissipation in the SRAM.
    Type: Grant
    Filed: August 22, 1986
    Date of Patent: September 27, 1988
    Assignee: Hitachi, Ltd.
    Inventors: Shuji Ikeda, Satoshi Meguro, Kotaro Nishimura, Sho Yamamoto, Nobuyoshi Tanimura
  • Patent number: 4760561
    Abstract: An MOS static type RAM has a memory cell array comprising a plurality of static type memory cells arranged in matrix, a plurality of data lines connected to the data input-output terminals of the respective memory cells and a plurality of word lines connected to the selection terminals of the respective memory cells. Data line load circuits are disposed between the power terminal of the circuit and the data lines. Each data line load circuit is kept at a relatively high impedance in the data write-in operation, and at a relatively low impedance in the data read-out operation. The use of the data line load circuits comprised of such variable impedance circuits can speed up the operating speed of the RAM and can accomplish lower power consumption.
    Type: Grant
    Filed: June 3, 1985
    Date of Patent: July 26, 1988
    Assignees: Hitachi, Ltd., Hitachi Microcomputer Eng.
    Inventors: Sho Yamamoto, Osamu Minato, Makoto Saeki, Yasuo Yoshitomi, Hideaki Nakamura, Masaaki Kubotera
  • Patent number: 4509147
    Abstract: In a static type RAM, a sense amplifier includes first and second dissymmetric type differential amplifier circuits each of which has a pair of differential transistors and an active load circuit such as a current mirror circuit connected to the drains of the differential transistors. One of balanced signals delivered from a memory cell is supplied to the non-inverting input terminal of the first dissymmetric type differential amplifier circuit and the inverting input terminal of the second dissymmetric type differential amplifier circuit. The other of said balanced signals is applied to the remaining input terminals of the first and second dissymmetric type differential amplifier circuits. As a result, notwithstanding that balanced signals cannot be delivered from each dissymmetric type differential amplifier circuit, amplified balanced signals can be obtained.
    Type: Grant
    Filed: June 1, 1982
    Date of Patent: April 2, 1985
    Assignees: Hitachi, Ltd., Hitachi Microcomputer Engineering, Ltd.
    Inventors: Nobuyoshi Tanimura, Sho Yamamoto, Kazuo Yoshizaki, Isao Akima