Patents by Inventor Shooji Kitazawa

Shooji Kitazawa 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: 6233168
    Abstract: A non-volatile semiconductor memory decreases a parasitic current as much as possible without using an electric separation means. This nonvolatile semiconductor storage apparatus has multiple memory cells rows having multiple memory cell transistors M1, M2 . . . whose gates are connected to word lines WL1, WL2 . . . , respectively, and whose sources and drains are serially connected. This non-volatile semiconductor storage apparatus also has multiple column lines SBL0, SVL0, SVL1, SBL1 . . . which connect the connection nodes between the sources and drains of the memory cell transistors M1, M2 . . .
    Type: Grant
    Filed: August 11, 1999
    Date of Patent: May 15, 2001
    Assignee: Oki Electric Industry Co., Ltd.
    Inventors: Hitoshi Kokubun, Shooji Kitazawa, Keiichiro Takeda, Yuichi Ashizawa
  • Patent number: 6147912
    Abstract: A non-volatile semiconductor memory apparatus having a memory matrix of inter-column arrangement type configuration divided into several segments performs a read operation based on a system that causes a current to flow into sense amplifiers from data lines. In this non-volatile semiconductor memory, memory cell transistors configured as memory cells are serially connected to form multiple memory rows. Word lines connect the gates of the transistors constituting the memory cells of each memory row. First column lines and second column lines connect the connection nodes between the memory cell transistors. The word lines and the first and second column lines constitute a memory array. Bit lines are connected to the second column lines, respectively. A bias electric potential supply line is connected to the first column lines via select transistors, respectively.
    Type: Grant
    Filed: January 8, 1999
    Date of Patent: November 14, 2000
    Assignee: Oki Electric Industry Co., Ltd.
    Inventor: Shooji Kitazawa
  • Patent number: 5204542
    Abstract: A read-only semiconductor memory device including memory elements arranged in a principal surface of the semiconductor substrate in a matrix to form MOS transistors. Each of the memory elements has first and second electrode regions formed in the principal surface so as to respectively constitute the first and second electrodes, insulative layers formed on the principal surface, and a control electrode layer formed via the insulative layers on the principal surface to constitute the control electrode. The control electrode layer is commonly connected to memory elements in the lateral direction of the matrix. The first and second electrode regions are respectively arranged such that any adjacent two in the vertical direction of the memory elements electrically share the first and second electrodes, respectively. Each of the first electrode regions is interconnected to the first electrode region of one of the elements adjacent thereto in the lateral direction.
    Type: Grant
    Filed: October 25, 1991
    Date of Patent: April 20, 1993
    Assignee: Oki Electric Industry Co., Ltd.
    Inventors: Satoru Namaki, Shooji Kitazawa, Teruhiro Harada
  • Patent number: 5056062
    Abstract: A method of operating an EPROM which has a word line, a predecode circuit having an ou tput terminal and a transistor having a first electrode connected to the output terminal of the predecode circuit, a second electrode connected to a word line and a control gate. The method of operating the EPROM includes generating a selection signal and an inverted signal thereof in accordance with an internal address signal, and generating a delayed signal responsive to the selection signal and the inverted signal so that the delayed signal rises by a predetermined time delay behind a rising of the selection signal and rapidly falls substantially simultaneously with a rising of the inverted signal. Thereafter the potential of the selection signal is boosted in accordance with a potential of the delayed signal and the boosted selection signal is supplied to the control gate of the transistor connected between the predecode circuit and the word line.
    Type: Grant
    Filed: June 29, 1990
    Date of Patent: October 8, 1991
    Assignee: Oki Electric Industry Co., Ltd.
    Inventors: Hiroshi Kuwabara, Shooji Kitazawa
  • Patent number: 5051953
    Abstract: An electrically erasable nonvolatile semiconductor device of a high density of integration includes a memory matrix array formed of a plurality of MOS memory transistors. In an erasing operation, a voltage to turn off one selected MOS memory transistor is applied to the control gate electrode of the selected MOS memory transistor. At the same time, a voltage near the breakdown voltage of the selected MOS memory transistor is applied to the first electrode (e.g.--source electrode) of the selected MOS memory transistor and a predetermined voltage is applied to the second electrode (e.g.--drain electrode) of the same MOS memory transistor.
    Type: Grant
    Filed: December 18, 1989
    Date of Patent: September 24, 1991
    Assignee: Oki Electric Industry Co., Ltd.
    Inventors: Shooji Kitazawa, Takashi Ono
  • Patent number: 5031148
    Abstract: In a memory MOS semiconductor memory device comprising a memory matrix having semiconductor memory elements arranged in rows and columns, the memory elements in the same rows being connected to the respective word lines, and the memory elements in the same columns being connected to the respective source lines and data lines. A row decoder outputs a row selection signal to one of the rows of the memory elements through the word lines, while a column decoder outputs a column selection signal to one of the columns through the source lines. A common data line is electrically coupled to a plurality of the data lines, a constant voltage is applied from a common circuit to the data lines through the common data line, and the current required for maintaining the common data line at a constant voltage is detected by a detecting circuit.
    Type: Grant
    Filed: July 19, 1989
    Date of Patent: July 9, 1991
    Assignee: Oki Electric Industry Co., Ltd.
    Inventors: Shooji Kitazawa, Teruhiro Harada
  • Patent number: 4987464
    Abstract: In a semiconductor device having an external input terminal, a first insulated-gate field-effect transistor formed on a semiconductor substrate, and having a gate connected to the input terminal, and a second insulated-gate field effect transistor having a drain connected to the gate of the first insulated-gate field-effect transistor, and having a gate and source connected to a reference voltage source, the ratio W/L of the channel width W to the channel length L of the second insulated-gate field effect transistor is not less than 12.
    Type: Grant
    Filed: February 2, 1990
    Date of Patent: January 22, 1991
    Assignee: Oki Electric Industry Co., Ltd.
    Inventors: Yasuhiro Fukuda, Shooji Kitazawa
  • Patent number: 4967399
    Abstract: Am EPROM system comprising a memory cell array formed of a matrix of non-volatile semiconductor memory cells, each having a control gate and a floating gate, and storing electric charges on the floating gate, and a word line drive circuit driving respective word lines connected to the control gates of the respective memory cells. The word line drive circuit comprises a delay circuit for delaying a first selection signal, a boosting capacitor having a first electrode connected to the first selection signal and a second electrode connected the output of the delay circuit, and MOS transistors each having a gate electrode connected the second electrode of the boosting capacitor, a first electrode connected to receive a second selection signal and a second electrode connected to a word line.
    Type: Grant
    Filed: July 28, 1988
    Date of Patent: October 30, 1990
    Assignee: OKI Electric Industry Co., Ltd
    Inventors: Hiroshi Kuwabara, Shooji Kitazawa
  • Patent number: 4935791
    Abstract: A read-only semiconductor memory device including memory elements arranged in a principal surface of the semiconductor substrate in a matrix to form MOS transistors. Each of the memory elements has first and second electrode regions formed in the principal surface so as to respectively constitute the first and second electrodes, insulative layers formed on the principal surface, and a control electrode layer formed via the insulative layers on the principal surface to constitute the control electrode. The control electrode layer is commonly connected to memory elements in the lateral direction of the matrix. The first and second electrode regions are respectively arranged such that any adjacent two in the vertical direction of the memory elements electrically share the first and second electrodes, respectively. Each of the first electrode regions is interconnected to the first electrode region of one of the elements adjacent thereto in the lateral direction.
    Type: Grant
    Filed: January 9, 1989
    Date of Patent: June 19, 1990
    Assignee: Oki Electric Industry Co., Ltd.
    Inventors: Satoru Namaki, Shooji Kitazawa, Teruhiro Harada
  • Patent number: 4924280
    Abstract: In a semiconductor device having an external input terminal, a first insulated-gate field-effect transistor formed on a semiconductor substrate, and having a gate connected to the input terminal, and a second insulated-gate field effect transistor having a drain connected to the gate of the first insulated-gate field-effect transistor, and having a gate and source connected to a reference voltage source, the ratio W/L of the channel width W to the channel length L of the second insulated-gate field effect transistor is not less than 12.
    Type: Grant
    Filed: September 1, 1989
    Date of Patent: May 8, 1990
    Assignee: Oki Electric Industry Co., Ltd.
    Inventors: Yasuhiro Fukuda, Shooji Kitazawa
  • Patent number: 4899309
    Abstract: In a current sense circuit for detecting a read current from a selected memory cell in a memory cell matrix of a ROM, each of a first series circuit and a second series circuit comprises: a current supply means having a first main electrode connected to a power supply; a first MOS FET having a first main electrode connected to the second main electrode of the current supply means; and a second MOS FET having a first main electrode connected to the second main electrode of the first MOS FET, a second main electrode connected to a second power supply, and a gate electrode connected to the first main electrode of the first MOS FET.
    Type: Grant
    Filed: July 28, 1988
    Date of Patent: February 6, 1990
    Assignee: Oki Electric Co., Ltd.
    Inventors: Shooji Kitazawa, Hiroshi Kuwabara, Teruhiro Harada
  • Patent number: 4884239
    Abstract: The invention concerns a method for electrically erasing data stored in a FAMOS-type EPROM. That is, in an Electrically Programmable Read Only Memory of the Metal Oxide Semiconductor type in which a Floating gate is employed as a memory element and in which data-writing is effected by charge injection from a channel Avalanche current, the invention concerns a method for effectively removing such channel-injected charge from a subject written floating gate. The method specifically entails the injection into the written gate of neutralizational opposing-polarity hot carriers from a generated reverse avalanche current between th MOS drain and substrate. The drain avalanche, however, is limited to "non-breakdown" levels by a technique which, in addition to appropriate drain biasing, includes suitable source and control-gate biasing so as to essentially prevent the flow of channel current during erasure.
    Type: Grant
    Filed: April 5, 1988
    Date of Patent: November 28, 1989
    Assignee: Oki Electric Industry Co., Ltd.
    Inventors: Takashi Ono, Shooji Kitazawa
  • Patent number: 4709352
    Abstract: A MOS ROM system is arranged such that during a readout operation a current flows from at least one data line selected from among a plurality of data lines. The read and sense circuit detects a memory state of a selected memory cell based on the amount of inflow current. A non-selected memory cell does not contribute to a word line load capacitance, and the word line load capacitance upon switching word lines can be reduced. A signal transfer rate can therefore be increased, and a data read rate can thereby be speeded up. Moreover, a read and sense circuit for a ROM is adapted such that first and third MOS transistors and a first current supply circuit, and second and fourth MOS transistors and a second current supply circuit are associated with each other, and each connected in series betweeen a low supply voltage and high supply voltage.
    Type: Grant
    Filed: November 15, 1985
    Date of Patent: November 24, 1987
    Assignee: OKI Electric Industry Co., Ltd.
    Inventor: Shooji Kitazawa