Patents by Inventor Shigeo Ohshima

Shigeo Ohshima 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: 6292430
    Abstract: A synchronous semiconductor memory device such as SDRAM easy in timing adjustment of column selection and capable of reducing cycle time and access time to be minimum value without reducing access margin is provided. The synchronous semiconductor memory device includes a memory cell array constituted in a matrix form, a command decoder and an address buffer operative in synchronism with the leading end of clock signal, a row decoder for decoding row address to select word line of the memory cell, a column control signal generating circuit for generating a column control signal, and a column decoder for taking thereinto column address taken in by the address buffer by a column address taking-in signal generated from the command decoder in synchronism with the leading end of the clock signal to allow a column select signal line to be active.
    Type: Grant
    Filed: March 15, 2000
    Date of Patent: September 18, 2001
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Hiroyuki Ohtake, Shigeo Ohshima
  • Patent number: 6292412
    Abstract: A clock synchronous circuit comprising a clock receiver, a delay monitor, a forward pulse delay circuit, a backward pulse delay circuit, a driver, a state-holding section, a control signal generating circuit, a first AND circuit, and a second AND circuit. The delay monitor delays the output of the clock receiver. The forward pulse delay circuit delays the output of the delay monitor. The backward pulse delay circuit delays the output of the clock receiver. The driver receives the output of the backward pulse delay circuit and outputs an internal clock signal. The state-holding section controls the backward pulse delay circuit. The control pulse generating circuit initializes the forward pulse delay circuit. The first AND circuit is provided for controlling the supply of the output of the clock receiver to the delay monitor. The second AND is provided for controlling the supply of the output of the delay monitor to the forward pulse delay circuit.
    Type: Grant
    Filed: June 30, 2000
    Date of Patent: September 18, 2001
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Koji Kato, Masahiro Kamoshida, Shigeo Ohshima, Hiroyuki Ohtake
  • Patent number: 6260128
    Abstract: A clock signal is supplied to an input buffer circuit. A delay circuit has a delay time equal to a difference between the cycle time for latency (CL) of 3 and the cycle time for latency of 2. When CL=2, a transfer gate outputs a clock signal delayed by the delay circuit, as a clock signal CLK2. The clock signal CLK2 initiates the operation in the second stage at the latency of 3. The operation at the latency of 2 can, therefore, be performed in a cycle time having a sufficient margin, without increasing the speed of the operation in the second stage at the latency of 3.
    Type: Grant
    Filed: August 11, 1998
    Date of Patent: July 10, 2001
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Shigeo Ohshima, Shinji Miyamoto
  • Publication number: 20010006483
    Abstract: A row access command and column access command are supplied as one packet to an FCRAM in two successive clock cycles in order to shorten random access time and random cycle time. At this time, definition of the read/write operation is made by use of a first command and a decode address of a memory cell array is fetched in response to the first command. When the decode address of the memory cell array is fetched in response to the first command, command control pins of the conventional SDR/DDR-SDRAM are used as address pins.
    Type: Application
    Filed: December 27, 2000
    Publication date: July 5, 2001
    Applicant: KABUSHIKI KAISHA TOSHIBA
    Inventors: Shigeo Ohshima, Nobuo Watanabe
  • Publication number: 20010005012
    Abstract: An input data register for latching write data is arranged in a position near a memory cell array of a memory core section. The input data register is arranged on the upstream side of a data path used for writing data into a memory cell. Write data input to a data pin which is arranged in the end position on the downstream side is latched in the input data register via a data input buffer, serial/parallel converting circuit and write data line. Data latched in the input data register is written into a memory cell via a DQ write driver, data line pair, I/O gate and bit line pair in a next write cycle.
    Type: Application
    Filed: December 13, 2000
    Publication date: June 28, 2001
    Applicant: KABUSHIKI KAISHA TOSHIBA
    Inventors: Shigeo Ohshima, Hiroyuki Ohtake, Katsumi Abe
  • Patent number: 6226204
    Abstract: The data output circuit in a clock synchronous DRAM comprises a first data transfer circuit to which the data read from a memory is input and which transfers the input data to the output side in synchronization with an internal clock, an equalizing circuit to which the output of the first data transfer circuit is input during a read operation by a burst operation and to which high-impedance data is input after the read operation, a second data transfer circuit connected to the equalizing circuit, and an output buffer to which the output of the second data transfer circuit is input. The second data transfer circuit transfers all the data to the output buffer in synchronization with an output clock. This eliminates the dependence of the data access time and data hold time on data item and/or cycle and facilitates the timing control of the output control signal.
    Type: Grant
    Filed: August 27, 1998
    Date of Patent: May 1, 2001
    Assignee: Kabushuki Kaisha Toshiba
    Inventors: Kazuko Inuzuka, Katsushi Nagaba, Shigeo Ohshima
  • Patent number: 6198690
    Abstract: A clock control circuit includes a forward pulse delay circuit including a plurality of delay circuits for delaying a forward pulse signal FCL, a backward pulse delay circuit including a plurality of delay circuits for delaying a backward pulse signal RCL, a state-hold section including a plurality of state-hold circuits for controlling the operation of the backward pulse delay circuit in accordance with the transmission condition of the forward pulse signal in the forward pulse delay circuit, and an input stop circuit for stopping inputting a pulse corresponding to an external clock signal to the backward pulse delay circuit during a predetermined period from the time point when the external clock signal begins to be supplied.
    Type: Grant
    Filed: February 14, 2000
    Date of Patent: March 6, 2001
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Koji Kato, Masahiro Kamoshida, Shigeo Ohshima
  • Patent number: 6163501
    Abstract: A synchronous semiconductor memory device comprises: a memory cell array; a decoder circuit for decoding an address, which is supplied in synchronism with a clock, to select a memory cell of the memory cell array; a plurality of main data line pairs, to which data of the memory cell array are transferred; a plurality of data line buffers, each of which is provided in a corresponding one of the main data line pairs and each of which includes a latch circuit; and a plurality of peripheral data lines for transferring data of each of the data line buffers to a data input/output terminal, wherein a plurality of bits of data per data input/output terminal read out of the memory cell array are transferred to the data line buffers via the main data line pairs in parallel, and while head data of the plurality of bits of data pass through the latch circuits to be transferred to one of the peripheral data lines, a plurality of continuous data are temporarily held by the latch circuit, and subsequent data are sequentiall
    Type: Grant
    Filed: March 8, 2000
    Date of Patent: December 19, 2000
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Shigeo Ohshima, Susumu Ozawa
  • Patent number: 6088290
    Abstract: When a clock enable signal asynchronous with a clock signal is set at a high level, a power-down control circuit sets a power-down signal at a high level to release a power-down mode. When the power-down mode is released, a clock control circuit outputs an internal clock signal such that an output signal of a command decoder can be latched. According to such a constitution, a period of time from the latching of the command after releasing the power-down mode to the time when the command can be transferred will be reduced, and a high-speed operation can be attained.
    Type: Grant
    Filed: August 11, 1998
    Date of Patent: July 11, 2000
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Hiroyuki Ohtake, Shigeo Ohshima, Takehiro Hasegawa
  • Patent number: 6046955
    Abstract: A synchronous dynamic random access memory has spare columns which can be tested before shipping. In the memory, a mode set register outputs a multibank write signal in the test mode. A CBS latch circuit generates not only a signal for selecting the spare column decoders in banks and in the test mode but also signals for selecting the column decoders. Write driving circuits write the data onto the column lines selected by the column decoders and onto the spare column lines selected by the spare column decoders.
    Type: Grant
    Filed: March 17, 1999
    Date of Patent: April 4, 2000
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Yasuhiro Suematsu, Shigeo Ohshima
  • Patent number: 5949090
    Abstract: A semiconductor integrated circuit includes a rectangular semiconductor chip having a main surface, a plurality of pads formed in a peripheral portion of the main surface of the semiconductor chip, for connection to external connecting members, a plurality of circuit elements of an integrated circuit formed in an area of the main surface other than an area in which the plurality of pads are formed, and at least one characteristic evaluating circuit element connected to at least one of the plurality of circuit elements of the integrated circuit by sharing an impurity doped region which forms part of the at least one circuit element with the at least one circuit element of the integrated circuit in an area of the main surface other than the peripheral portion in which the plurality of pads are formed.
    Type: Grant
    Filed: September 18, 1997
    Date of Patent: September 7, 1999
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Kiyoaki Iwasa, Shigeo Ohshima
  • Patent number: 5841730
    Abstract: A semiconductor memory device capable of shortening data reading time in a first read cycle after the mode has been changed from a write mode to a read mode while maintaining high-speed cycle time when data is written despite simple structure, the semiconductor memory device having a memory cell array having a plurality of dynamic memory cells, to which data can be written, data line pairs to which data read from the memory cells and data which must be written on the memory cells are transferred, a write driver for driving the data line pairs in accordance with write data supplied from outside when data is written to the memory cells and an equalizing circuit for setting the data line pairs to an intermediate potential whenever the data line pairs are operated by the write driver.
    Type: Grant
    Filed: January 29, 1997
    Date of Patent: November 24, 1998
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Yasuyuki Kai, Katsushi Nagaba, Shigeo Ohshima
  • Patent number: 5818785
    Abstract: A semiconductor memory device having a plurality of banks of memory cells is provided. The device has a data line provided in each of the banks for coupling to one of the memory cells in the corresponding bank. A common data line is shared by the banks, and is selectively coupled to one of the data lines through switches. Additionally, an amplifier is coupled to the common data line to amplify data read from a selected memory cell, and an I/O line is coupled to the amplifier to transmit the amplified data to an outer section. In the device, one of the banks of memory cells is selected by a bank select signal. Therefore, the amplifier is shared by the banks. Further the length of the I/O line can be shortened so that the load on the amplifier can be reduced. Accordingly, chip area is decreased and the speed of the memory device is improved.
    Type: Grant
    Filed: December 16, 1996
    Date of Patent: October 6, 1998
    Assignee: Kabushiki Kaisha Toshiba
    Inventor: Shigeo Ohshima
  • Patent number: 5777946
    Abstract: The present invention provides a semiconductor memory circuit capable of high-speed access to a predetermined column portion by a simplified high-speed addressing circuit. The memory circuit in a DRAM is such that a portion of a column addressing circuit normally comprising a counter constitutes a shift register in a column addressing circuit at a preceding stage of a column address buffer so that a plurality of address signal wrappings are realized for accessing the predetermined column portion.
    Type: Grant
    Filed: December 20, 1996
    Date of Patent: July 7, 1998
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Kazuko Inuzuka, Shigeo Ohshima, Katsushi Nagaba
  • Patent number: 5703381
    Abstract: A semiconductor integrated circuit includes a rectangular semiconductor chip having a main surface, a plurality of pads formed in a peripheral portion of the main surface of the semiconductor chip, for connection to external connecting members, a plurality of circuit elements of an integrated circuit formed in an area of the main surface other than an area in which the plurality of pads are formed, and at least one characteristic evaluating circuit element connected to at least one of the plurality of circuit elements of the integrated circuit by sharing an impurity doped region which forms part of the at least one circuit element with the at least one circuit element of the integrated circuit in an area of the main surface other than the peripheral portion in which the plurality of pads are formed.
    Type: Grant
    Filed: November 13, 1995
    Date of Patent: December 30, 1997
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Kiyoaki Iwasa, Shigeo Ohshima
  • Patent number: 5410512
    Abstract: A semiconductor memory device includes a silicon chip and sub-arrays formed in the chip. In each of the sub-arrays, memory cells arranged in a matrix form, word lines provided for respective rows of each of the sub-arrays, and bit lines provided for respective columns of each of the sub-arrays are arranged. Further, in the chip, amplifier groups for amplifying data read out from the memory cells are arranged for the respective sub-arrays. Amplifiers connected to respective bit lines are provided in the amplifier groups and the amplifiers each have a function of continuously holding data read out from the memory cell.
    Type: Grant
    Filed: May 21, 1993
    Date of Patent: April 25, 1995
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Satoru Takase, Tohru Furuyama, Donald C. Stark, Natsuki Kushiyama, Kiyofumi Sakurai, Hiroyuki Noji, Shigeo Ohshima
  • Patent number: 5311471
    Abstract: A semiconductor memory device including:a data storage device having a plurality of memory cells each capable of storing a data and being selected by an address, first complementary data corresponding to the data in a selected memory cell being outputted to first complementary data lines;a first equalizer for short-circuiting and equalizing the first complementary data lines;an amplifier for receiving the first complementary data from the first complementary data lines, making large the difference between levels of the first complementary data, and outputting as second complementary data the levels to second complementary data lines;a second equalizer for short-circuiting and equalizing the second complementary data lines;a data latch circuit having latch units and switching means, the latch unit receiving and latching the second complementary data from the second complementary data lines and outputting as third complementary data the second complementary data to third complementary data lines, the switching
    Type: Grant
    Filed: December 7, 1992
    Date of Patent: May 10, 1994
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Naoki Matsumoto, Yuji Wtanabe, Shigeo Ohshima
  • Patent number: 5287306
    Abstract: A semiconductor memory device includes a first power source having a non-ground potential V.sub.cc1 terminal and a ground potential V.sub.ss1 terminal. The internal circuit is supplied with power from the first power source. The first power source is dedicated to the internal circuit. The internal circuit selects a memory cell of a memory cell array in accordance with an inputted address. The internal circuit has a first output terminal and a second output terminal the first output terminal outputs one of a pair of potential V.sub.cc1 and V.sub.ss1 and the second output terminal outputs the other of the pair in accordance with the data in the selected memory cell. A second power source has a non-ground potential V.sub.cc2 terminal and a ground potential V.sub.ss2 terminal. The output circuit is supplied with power from the second power source which is dedicated to the output circuit. The output circuit has first and second transistors serially connected between the V.sub.cc2 terminal and V.sub.ss2.
    Type: Grant
    Filed: June 20, 1991
    Date of Patent: February 15, 1994
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Shinji Miyamoto, Shigeo Ohshima
  • Patent number: 5251180
    Abstract: In the semiconductor memory composed of divided dynamic memory cell arrays, when a drive signal is supplied to a word line selected by a row decoder, data stored at the memory cells connected to the word line are transferred to bit lines, respectively. A change in potential at the bit line pair is amplified by the sense amplifier to completely read the data. To prevent the bit line pairs from being sensed erroneously due to fluctuation of the timings at which the word line driving signals are generated in the divided cell arrays, a bit line sense signal is generated a predetermined delay time after all the word line driving signals have been generated, in order to drive all the sense amplifiers simultaneously, so that data can be definitely read from the memory cells to the bit lines.
    Type: Grant
    Filed: November 29, 1991
    Date of Patent: October 5, 1993
    Assignee: Kabushiki Kaisha Toshiba
    Inventor: Shigeo Ohshima
  • Patent number: 5239509
    Abstract: A semiconductor memory device having: a RAM port for randomly accessing a memory cell array having memory cells disposed in matrix; a SAM port for serially accessing data of one row of the memory cell array; a mode switching unit for switching the operation mode of the SAM port between an ordinary data output mode and a test mode, upon externally receiving a mode switching signal; and an address pointer outputting unit for outputting an address pointer of the SAM port when the operation mode is switched to the test mode by the mode switching unit.
    Type: Grant
    Filed: January 23, 1992
    Date of Patent: August 24, 1993
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Tatsuo Ikawa, Shigeo Ohshima