Patents by Inventor Takeshi Kajimoto

Takeshi Kajimoto 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: 5659260
    Abstract: A negative power supply circuit is connected via an NMOS transistor to a node receiving ground potential in a sense amplifier. A one shot pulse generation circuit provides a one shot pulse signal to the gate of the NMOS transistor. The NMOS transistor is turned on when a one shot pulse signal is applied to connect the negative power supply circuit to the node. This causes the potential of the node to be lowered to a negative potential. As a result, increase in the potential at the ground side of the sense amplifier caused by an interconnection resistance in the ground interconnection is suppressed. Therefore, variation in the potential received by the sense amplifier due to interconnection resistance can be suppressed.
    Type: Grant
    Filed: February 20, 1996
    Date of Patent: August 19, 1997
    Assignee: Mitsubishi Denki Kabushiki Kaisha
    Inventors: Takeshi Kajimoto, Hiroshi Akamatsu
  • Patent number: 5600281
    Abstract: In a semiconductor memory device, a constant voltage is applied to a resistor having a positive temperature coefficient, whereby a first reference current flowing through that resistor is converted into a voltage by a resistor. That voltage is converted into a second reference current by a P channel MOS transistor, whereby a second current of a value equal to the value of the second reference current flows through each of a plurality of inverters by a current mirror circuit. These inverters are connected in a ring manner to form a ring oscillator. The first reference current becomes lower as the operating temperature rises, whereby the second reference current increases. As a result, the oscillator cycle of the ring oscillator becomes shorter as the operating temperature rises.
    Type: Grant
    Filed: December 22, 1995
    Date of Patent: February 4, 1997
    Assignee: Mitsubishi Denki Kabushiki Kaisha
    Inventors: Shigeru Mori, Takeshi Kajimoto, Masanori Hayashikoshi
  • Patent number: 5594704
    Abstract: Memory arrays are divided into banks which can be operated independent from each other. Read data storing registers and write data storing registers operating independent from each other are provided for the banks. The memory array is divided into a plurality of small array blocks, local IO lines are arranged corresponding to each array block, and the local IO lines are connected to global IO lines. The global IO lines are connected to preamplifier groups and to write buffer groups. By control signal generating circuits and by a register control circuit, inhibition of writing of a desired bit only during successive writing operation can be done, data can be collectively written to the selected memory cells when the final data is input if the data writing should be stopped before reaching the wrap length in successive writing, and the timing for activating the memory array when the write cycle should be repeatedly carried out can be delayed.
    Type: Grant
    Filed: April 10, 1995
    Date of Patent: January 14, 1997
    Assignee: Mitsubishi Denki Kabushiki Kaisha
    Inventors: Yasuhiro Konishi, Takayuki Miyamoto, Takeshi Kajimoto, Hisashi Iwamoto
  • Patent number: 5557193
    Abstract: A method and an apparatus of an internal voltage down converter having good transient response characteristics and small chip real estate, includes a differential amplifier for comparing a voltage on an internal power supply line with a reference voltage, a MOS transistor for generating an internal supply voltage from an external supply voltage, by receiving the output of the differential amplifier at the gate, and a feed back capacitive element provided between the internal power supply line and the gate of the MOS transistor.
    Type: Grant
    Filed: September 27, 1993
    Date of Patent: September 17, 1996
    Assignee: Mitsubishi Denki Kabushiki Kaisha
    Inventor: Takeshi Kajimoto
  • Patent number: 5539353
    Abstract: A differential amplifier and an NMOS transistor are provided corresponding to each load circuit. A positive input and a negative input of the differential amplifier are coupled to a first ground interconnection and a second ground interconnection, respectively. When the selected load circuit operates, the potential received by this load circuit rises by interconnection resistances of the first ground interconnection. However, the potential received by the de-selected load circuit is reduced due to the operation of its corresponding differential amplifier and transistor. As a result, a rise in the potential of the de-selected circuit caused by the operation of the selected circuit will be suppressed. The differential amplifier and transistor corresponding to the selected load circuit also operate to reduce the potential of the selected circuit, thereby to suppress the rise in such potential.
    Type: Grant
    Filed: August 5, 1994
    Date of Patent: July 23, 1996
    Assignee: Mitsubishi Denki Kabushiki Kaisha
    Inventors: Takeshi Kajimoto, Hiroshi Akamatsu
  • Patent number: 5530640
    Abstract: A voltage generation circuit has a charge pump circuit, a clamping circuit for clamping an output voltage of the charge pump circuit, and detecting means for detecting the output voltage of the charge pump circuit and supplying a control signal for boosting the output voltage to the charge pump circuit when the detected output voltage is lower than a reference voltage, wherein the detecting means includes a circuit for stopping supply of a control signal. This circuit stops supply of the control signal to the charge pump circuit when the clamping circuit is in operation.
    Type: Grant
    Filed: October 13, 1993
    Date of Patent: June 25, 1996
    Assignee: Mitsubishi Denki Kabushiki Kaisha
    Inventors: Motoko Hara, Takeshi Kajimoto
  • Patent number: 5530397
    Abstract: A reference voltage generating circuit of a DRAM includes a current mirror circuit constituted of first to fourth transistors. The gate of the third transistor is connected to the source of a fifth transistor. When a zero-power on reset signal, which becomes L on turn-on of the power supply, and becomes H after a predetermined period, is applied to the gate of the fifth transistor, and an external power supply voltage is forced to be applied to the gate of the third transistor on turn-on of the power supply, a reference voltage following the rise of the external power supply voltage is provided from the output of the current mirror circuit.
    Type: Grant
    Filed: July 27, 1994
    Date of Patent: June 25, 1996
    Assignee: Mitsubishi Denki Kabushiki Kaisha
    Inventors: Jun Nakai, Yuto Ikeda, Takeshi Kajimoto, Yuichiro Komiya
  • Patent number: 5499214
    Abstract: In a semiconductor memory device, a constant voltage is applied to a resistor having a positive temperature coefficient, whereby a first reference current flowing through that resistor is converted into a voltage by a resistor. That voltage is converted into a second reference current by a P channel MOS transistor, whereby a second current of a value equal to the value of the second reference current flows through each of a plurality of inverters by a current mirror circuit. These inverters are connected in a ring manner to form a ring oscillator. The first reference current becomes lower as the operating temperature rises, whereby the second reference current increases. As a result, the oscillator cycle of the ring oscillator becomes shorter as the operating temperature rises.
    Type: Grant
    Filed: June 10, 1994
    Date of Patent: March 12, 1996
    Assignee: Mitsubishi Denki Kabushiki Kaisha
    Inventors: Shigeru Mori, Takeshi Kajimoto, Masanori Hayashikoshi
  • Patent number: 5490119
    Abstract: A semiconductor memory device includes a pull up circuit (811) for pulling up a potential of a first node (812), a pull down circuit (813) for pulling down the potential of the first node, an inverter circuit (814b) having its input connected to a first input node (814a) connected to the first node (812) and its output connected to a first output node (814c) and operating with a boosted potential Vpp, and a p channel MOS transistor (814d) connected between a boosted potential node (50c) and the first input node (814a), with its gate electrode connected to the first output node (814c). The memory device provides a signal having a higher level than the supply potential with smaller area of layout.
    Type: Grant
    Filed: April 18, 1994
    Date of Patent: February 6, 1996
    Assignees: Mitsubishi Denki Kabushiki Kaisha, Mitsubishi Electric Engineering Co., Ltd.
    Inventors: Mikio Sakurai, Kenji Tokami, Kazuhiro Sakemi, Yutaka Ikeda, Yoshinori Inoue, Takeshi Kajimoto
  • Patent number: 5467315
    Abstract: The semiconductor memory is facilitated with control circuitry for effecting plural self-refresh modes having respectively different refresh periods. The plural self-refresh modes are typified by a PS (pseudo) refresh mode which is applied when the memory is in the nonselected state for a comparatively long period of time, such as in the state in which memory backup is being facilitated, and by a VS (virtual) refresh mode in which the refreshing operation of the memory cells is effected intermittently during the intervals of memory accessings. The pseudo refresh mode has a longer refresh time period than the virtual refresh mode. The control circuitry also has counter circuits for the generating of refresh address signals in accordance with a first timing signal indicative of a pseudo refresh mode and a second timing signal indicative of a virtual refresh mode, the latter timing signal being a higher frequency signal.
    Type: Grant
    Filed: April 28, 1994
    Date of Patent: November 14, 1995
    Assignees: Hitachi, Ltd., Hitachi VLSI Engineering Corp.
    Inventors: Takeshi Kajimoto, Yutaka Shimbo, Katsuyuki Sato, Masahiro Ogata, Kanehide Kenmizaki, Shouji Kubono, Nobuo Kato, Kiichi Manita, Michitaro Kanamitsu
  • Patent number: 5463249
    Abstract: In an electronic circuit system unit having a semiconductor integrated circuit unit on a wafer scale, a semiconductor wafer (a semiconductor integrated circuit unit on a wafer scale) and a print wiring substrate are laid to overlap each other and semiconductor pellets are mounted on the print wiring substrate in the overlapping area of the print wiring substrate and the semiconductor wafer. In said electronic circuit system unit, an area being a part of the periphery of the semiconductor wafer is protruded from the periphery of the print wiring substrate being placed to overlap the semiconductor wafer, and the semiconductor wafer and the print wiring substrate are electrically connected to each other in an area being a part of the protruded part through wires.
    Type: Grant
    Filed: November 24, 1992
    Date of Patent: October 31, 1995
    Assignee: Hitachi, Ltd.
    Inventors: Yutaka Shinbo, Takeshi Kajimoto, Mitsuteru Kobayashi, Katsuyuki Sato
  • Patent number: 5446418
    Abstract: A ring oscillator according to the invention includes a plurality of inverters cascade-connected between an input node and an output node. Each inverter includes four transistors connected in series between a power supply node and a ground node. A first pair of transistors each have a channel sized to have an input capacitance for delaying the signal of a preceding stage inverter for a prescribed time period. A second pair of transistors are coupled to a current mirror circuit and limits current flowing through the first pair of transistors. Thus, power consumption for obtaining a signal in a prescribed cycle is reduced.
    Type: Grant
    Filed: November 5, 1993
    Date of Patent: August 29, 1995
    Assignee: Mitsubishi Denki Kabushiki Kaisha
    Inventors: Motoko Hara, Takeshi Kajimoto
  • Patent number: 5442277
    Abstract: An internal power supply circuit includes a main internal power supply potential generating circuit for generating an internal power supply potential based on a prescribed reference potential, and an auxiliary internal power supply potential generating circuit which is activated in response to a control signal and when activated, generating an internal power supply potential together with the main internal power supply potential generating circuit. The auxiliary internal power supply potential generating circuit includes a P channel MOS transistor for driving, a differential amplifying circuit for controlling the driving transistor by comparing the internal power supply potential with the reference potential and a standby potential supplying circuit for applying a standby potential which is slightly higher than the threshold potential at the which the transistor is rendered conductive, to the gate of the driving transistor while the differential amplifying circuit is not activated.
    Type: Grant
    Filed: February 15, 1994
    Date of Patent: August 15, 1995
    Assignee: Mitsubishi Denki Kabushiki Kaisha
    Inventors: Shigeru Mori, Takeshi Kajimoto
  • Patent number: 5436552
    Abstract: A clamping circuit includes a constant current circuit including a constant current source and a current mirror circuit a trimmable resistance receiving a constant current from the constant current circuit, and a clamping MOS transistor receiving a voltage generated by the trimmable resistance at its gate to regulate a current flowing through a clamping node. It is possible to make rapid a current-voltage characteristic of the clamping circuit, and to set an arbitrary clamping potential.
    Type: Grant
    Filed: September 21, 1993
    Date of Patent: July 25, 1995
    Assignee: Mitsubishi Denki Kabushiki Kaisha
    Inventor: Takeshi Kajimoto
  • Patent number: 5420824
    Abstract: In LSI circuit devices having a plurality of subchips packaged therein and having specific functions, capacitance cutting buffer circuits are employed in conjunction with respective terminals of the subchips, and a driver is disposed at respective points where relatively long wiring lines are respectively sub-divided into a corresponding plurality of lines. As a result, signal transmission delay can be significantly reduced. The terminals of the subchips are also provided with a probing pad to test the operations of the subchips independently of one another. The subchips employ circuit blocks which are to operate simultaneously and in conjunction with the wirings of the subchips, power supply lines are disposed correspondingly to the distributively arranged circuit blocks. Bus lines also controllably transmit addresses as well as data signals in a time sharing manner. Furthermore, each of the subchips has a fault test circuit.
    Type: Grant
    Filed: January 12, 1994
    Date of Patent: May 30, 1995
    Assignee: Hitachi, Ltd.
    Inventors: Takeshi Kajimoto, Mitsuteru Kobayashi, Katsuyuki Sato, Yutaka Shimbo
  • Patent number: 5412604
    Abstract: A level converting unit outputs a signal at a ground potential GND or at a boosted power supply voltage V.sub.PP level in response to a control signal. In response to a control signal BLIM, a first level selecting unit outputs a signal at the ground potential GND or at a power supply voltage V.sub.CC level. A second level selecting unit outputs a predetermined signal from a signal at the boosted voltage V.sub.PP level of the level converting unit, a signal at the ground potential GND of the first level selecting unit, and a signal at the power supply voltage V.sub.CC level as a shared sense amplifier control signal in response to each above-described control signal. As a result, when the shared sense amplifier control signal is pulled up to the boosted voltage V.sub.PP level, it is possible to pull up the shared sense amplifier control signal to the power supply voltage V.sub.CC level, and then to the boosted voltage V.sub.PP level.
    Type: Grant
    Filed: May 26, 1994
    Date of Patent: May 2, 1995
    Assignee: Mitsubishi Denki Kabushiki kaisha
    Inventors: Tatsuya Fukuda, Takeshi Kajimoto
  • Patent number: 5391979
    Abstract: The constant current generating circuit includes a high resistance element for generating a very small current. This very small current is supplied to a first MOS transistor having a sufficiently large gate width to gate length ratio. The gate-source voltage of the first MOS transistor becomes its threshold voltage VTH, and the voltage applied across a resistance connected between the gate of the first MOS transistor and the ground line is set to a constant value VTH. Thus, a constant current is normally passed through the resistance. Since the very small current is supplied from the high resistance element which is normally turned on, regardless of the change of the power supply voltage, a constant current can be generated stably.
    Type: Grant
    Filed: October 13, 1993
    Date of Patent: February 21, 1995
    Assignee: Mitsubishi Denki Kabushiki Kaisha
    Inventors: Takeshi Kajimoto, Takayuki Miyamoto
  • Patent number: 5384745
    Abstract: Memory arrays are divided into banks which can be operated independent from each other. Read data storing registers and write data storing registers operating independent from each other are provided for the banks. The memory array is divided into a plurality of small array blocks, local IO lines are arranged corresponding to each array block, and the local IO lines are connected to global IO lines. The global IO lines are connected to preamplifier groups and to write buffer groups. By control signal generating circuits and by a register control circuit, inhibition of writing of a desired bit only during successive writing operation can be done, data can be collectively written to the selected memory cells when the final data is input if the data writing should be stopped before reaching the wrap length in successive writing, and the timing for activating the memory array when the write cycle should be repeatedly carried out can be delayed.
    Type: Grant
    Filed: April 14, 1993
    Date of Patent: January 24, 1995
    Assignee: Mitsubishi Denki Kabushiki Kaisha
    Inventors: Yasuhiro Konishi, Takayuki Miyamoto, Takeshi Kajimoto, Hisashi Iwamoto
  • Patent number: 5381367
    Abstract: First and second input/output line groups are provided. A plurality of first bit line groups are connected to the first input/output line group through corresponding column selecting circuits, respectively. A plurality of second bit line groups are connected to the second input/output line group through corresponding column selecting circuits, respectively. A column decoder activates one of the column selecting circuits corresponding to the first bit line group and one of the column selecting circuits corresponding to the second bit line group at the same time or with a predetermined time difference.
    Type: Grant
    Filed: March 24, 1993
    Date of Patent: January 10, 1995
    Assignee: Mitsubishi Denki Kabushiki Kaisha
    Inventor: Takeshi Kajimoto
  • Patent number: 5357416
    Abstract: An improved substrate bias voltage generating circuit provided in a semiconductor device such as a DRAM is disclosed. In a conducting period of an NMOS transistor (8) provided in a last stage, a higher enough voltage than a source voltage (i.e. an output voltage V.sub.BB) can be applied to a gate of the transistor (8). Loss for a threshold voltage of the transistor (8) does not occur in the output voltage V.sub.BB ; the substrate bias voltage V.sub.BB of a level -Vcc can be generated.
    Type: Grant
    Filed: June 4, 1993
    Date of Patent: October 18, 1994
    Assignee: Mitsubishi Denki Kabushiki Kaisha
    Inventors: Toshihiro Kitano, Takeshi Kajimoto