Patents by Inventor Yasuhiko Maki

Yasuhiko Maki 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: 7995407
    Abstract: A semiconductor memory device comprising a regular cell array that includes a regular memory cell to which one of a first power supply voltage and a second power supply voltage is supplied and to which a third power supply voltage is supplied, a redundant cell array that includes a redundant memory cell to which one of the first power supply voltage and the second power supply voltage is supplied and to which the third power supply voltage is supplied, and a power supply control circuit that controls supply of the first power supply voltage and the second power supply voltage to the regular cell array and the redundant cell array, wherein a difference between the second power supply voltage and the third power supply voltage is smaller than a difference between the first power supply voltage and the third power supply voltage.
    Type: Grant
    Filed: July 22, 2008
    Date of Patent: August 9, 2011
    Assignee: Fujitsu Semiconductor Limited
    Inventor: Yasuhiko Maki
  • Publication number: 20090046523
    Abstract: A semiconductor memory device comprising a regular cell array that includes a regular memory cell to which one of a first power supply voltage and a second power supply voltage is supplied and to which a third power supply voltage is supplied, a redundant cell array that includes a redundant memory cell to which one of the first power supply voltage and the second power supply voltage is supplied and to which the third power supply voltage is supplied, and a power supply control circuit that controls supply of the first power supply voltage and the second power supply voltage to the regular cell array and the redundant cell array, wherein a difference between the second power supply voltage and the third power supply voltage is smaller than a difference between the first power supply voltage and the third power supply voltage.
    Type: Application
    Filed: July 22, 2008
    Publication date: February 19, 2009
    Applicant: Fujitsu Limited
    Inventor: Yasuhiko MAKI
  • Patent number: 7457182
    Abstract: A semiconductor memory including a sense amplifier circuit for reading the data stored in memory cells and particularly to a semiconductor memory including a self-timing circuit for improving margin for reading data by controlling activation timing of the sense amplifier drive signal in accordance with characteristics of internal memory cells.
    Type: Grant
    Filed: May 23, 2006
    Date of Patent: November 25, 2008
    Assignee: Fujitsu Limited
    Inventors: Yasuhiko Maki, Toshiyuki Uetake
  • Patent number: 7447058
    Abstract: Each memory cell has a pair of inverters whose inputs and outputs are connected to each other and holds complementary data respectively in storage nodes which are outputs of the inverters. In a write operation during which the complementary data are written to the storage nodes respectively, the power control circuit sets a power supply voltage of the inverter having the storage node to which low level is written lower than a power supply voltage of the inverter having the storage node to which high level is written. Since power supply capability to the inverter having the storage node to which the low level is written lowers, the voltage of the storage node easily changes to the low level. That is, a write margin of a memory cell can be improved.
    Type: Grant
    Filed: January 30, 2006
    Date of Patent: November 4, 2008
    Assignee: Fujitsu Limited
    Inventors: Yasuhiko Maki, Koji Shimosako
  • Patent number: 7421364
    Abstract: An integrated circuit device of the invention, has a memory macro which during normal operation latches an input address in response to a control pulse and generates data output corresponding to the input address, and a test control circuit 22 which during testing performs memory macro characteristic tests. A ring oscillator is configured by connecting a prescribed number of stages including one or more memory macro units, having a memory macro and a pulse generation circuit which during testing generates a control pulse for tests in response to an input pulse, and the test control circuit measures the oscillation frequency or period of the ring oscillator.
    Type: Grant
    Filed: January 20, 2006
    Date of Patent: September 2, 2008
    Assignee: Fujitsu Limited
    Inventor: Yasuhiko Maki
  • Patent number: 7411813
    Abstract: In case that data are written in a flip-flop circuit by inverting the voltage to be supplied to a pair of write bit lines, the peak of the current waveform flowing in the pair of write bit lines is to be made gentler, whereby reduced power source noise and low power consumption should be achieved. To this end in a semiconductor device wherein flip-flop circuit for holding data, a memory cell including a transfer gate, a pair of write bit lines for writing data in the memory cell, are provided, in case that data are written in the flip-flop circuit by inverting the voltage to be supplied to the pair of write bit lines, the slew rate of the voltage to be supplied to the pair of write bit lines is made equal to predetermined value or less.
    Type: Grant
    Filed: November 1, 2004
    Date of Patent: August 12, 2008
    Assignee: Fujitsu Limited
    Inventor: Yasuhiko Maki
  • Patent number: 7327599
    Abstract: Included are first and second inverters 1L, 1R, a first selection transistor N1 controlling a connection of an output terminal of the first inverter 1L to a bit line 11, and a second selection transistor N2 controlling a connection of an output terminal of the second inverter 1R to a bit line 12, wherein the first inverter 1L having a first load transistor P1 and a first drive transistor N3 and the second inverter 1R having a second load transistor P2 and a second drive transistor N4, function as a memory cell 1, and a ratio of a driving current quantity that can be outputted in an ON-state of the first drive transistor N3 to a driving current quantity that can be outputted in an ON-state of the first selection transistor N1, is larger than a first predetermined value.
    Type: Grant
    Filed: July 28, 2006
    Date of Patent: February 5, 2008
    Assignee: Fujitsu Limited
    Inventor: Yasuhiko Maki
  • Publication number: 20070201263
    Abstract: Included are first and second inverters 1L, 1R, a first selection transistor N1 controlling a connection of an output terminal of the first inverter 1L to a bit line 11, and a second selection transistor N2 controlling a connection of an output terminal of the second inverter 1R to a bit line 12, wherein the first inverter 1L having a first load transistor P1 and a first drive transistor N3 and the second inverter 1R having a second load transistor P2 and a second drive transistor N4, function as a memory cell 1, and a ratio of a driving current quantity that can be outputted in an ON-state of the first drive transistor N3 to a driving current quantity that can be outputted in an ON-state of the first selection transistor N1, is larger than a first predetermined value.
    Type: Application
    Filed: July 28, 2006
    Publication date: August 30, 2007
    Inventor: Yasuhiko Maki
  • Publication number: 20070081407
    Abstract: Each memory cell has a pair of inverters whose inputs and outputs are connected to each other and holds complementary data respectively in storage nodes which are outputs of the inverters. In a write operation during which the complementary data are written to the storage nodes respectively, the power control circuit sets a power supply voltage of the inverter having the storage node to which low level is written lower than a power supply voltage of the inverter having the storage node to which high level is written. Since power supply capability to the inverter having the storage node to which the low level is written lowers, the voltage of the storage node easily changes to the low level. That is, a write margin of a memory cell can be improved.
    Type: Application
    Filed: January 30, 2006
    Publication date: April 12, 2007
    Inventors: Yasuhiko Maki, Koji Shimosako
  • Publication number: 20060239094
    Abstract: A semiconductor memory including a sense amplifier circuit for reading the data stored in memory cells and particularly to a semiconductor memory including a self-timing circuit for improving margin for reading data by controlling activation timing of the sense amplifier drive signal in accordance with characteristics of internal memory cells.
    Type: Application
    Filed: May 23, 2006
    Publication date: October 26, 2006
    Inventors: Yasuhiko Maki, Toshiyuki Uetake
  • Publication number: 20060126412
    Abstract: An integrated circuit device of the invention, has a memory macro which during normal operation latches an input address in response to a control pulse and generates data output corresponding to the input address, and a test control circuit 22 which during testing performs memory macro characteristic tests. A ring oscillator is configured by connecting a prescribed number of stages comprising one or more memory macro units, having a memory macro and a pulse generation circuit which during testing generates a control pulse for tests in response to an input pulse, and the test control circuit measures the oscillation frequency or period of the ring oscillator.
    Type: Application
    Filed: January 20, 2006
    Publication date: June 15, 2006
    Inventor: Yasuhiko Maki
  • Publication number: 20060013036
    Abstract: In case that data are written in a flip-flop circuit by inverting the voltage to be supplied to a pair of write bit lines, the peak of the current waveform flowing in the pair of write bit lines is to be made gentler, whereby reduced power source noise and low power consumption should be achieved. To this end in a semiconductor device wherein flip-flop circuit for holding data, a memory cell including a transfer gate, a pair of write bit lines for writing data in the memory cell, are provided, in case that data are written in the flip-flop circuit by inverting the voltage to be supplied to the pair of write bit lines, the slew rate of the voltage to be supplied to the pair of write bit lines is made equal to predetermined value or less.
    Type: Application
    Filed: November 1, 2004
    Publication date: January 19, 2006
    Inventor: Yasuhiko Maki
  • Patent number: 6870777
    Abstract: A semiconductor memory device includes a data access path for accessing a memory cell, a signal drive circuit which drives a signal on said data access path, a dummy path that emulates said data access path, and a dummy drive circuit which emulates said signal drive circuit, wherein said dummy path has a smaller load than said data access path, and said dummy drive circuit has a smaller drive capacity than said signal drive circuit.
    Type: Grant
    Filed: March 22, 2002
    Date of Patent: March 22, 2005
    Assignee: Fujitsu Limited
    Inventor: Yasuhiko Maki
  • Patent number: 6809404
    Abstract: A semiconductor device with laser-programmable fuses for repairing a memory defect found after production, in which guard rings and fuse patterns are designed to take up less chip space. The semiconductor device has a fuse pattern running parallel to the longitudinal axis of a rectangular guard ring, and patterns branching from the fuse pattern and drawn out of the guard ring in the direction perpendicular to that axis. The semiconductor device also has a plurality of memory cell arrays, each coupled to an I/O port for receiving and sending memory signals. One of those arrays is reserved as a redundant memory cell array for repair purposes. The device further has switch circuits for switching the connection between the I/O ports and memory cell arrays, selecting either default memory cell arrays of the I/O ports or their adjacent memory cell arrays, including the redundant memory cell array.
    Type: Grant
    Filed: March 24, 2003
    Date of Patent: October 26, 2004
    Assignee: Fujitsu Limited
    Inventor: Yasuhiko Maki
  • Publication number: 20030218932
    Abstract: A semiconductor device with laser-programmable fuses for repairing a memory defect found after production, in which guard rings and fuse patterns are designed to take up less chip space. The semiconductor device has a fuse pattern running parallel to the longitudinal axis of a rectangular guard ring, and patterns branching from the fuse pattern and drawn out of the guard ring in the direction perpendicular to that axis. The semiconductor device also has a plurality of memory cell arrays, each coupled to an I/O port for receiving and sending memory signals. One of those arrays is reserved as a redundant memory cell array for repair purposes. The device further has switch circuits for switching the connection between the I/O ports and memory cell arrays, selecting either default memory cell arrays of the I/O ports or their adjacent memory cell arrays, including the redundant memory cell array.
    Type: Application
    Filed: March 24, 2003
    Publication date: November 27, 2003
    Applicant: FUJITSU LIMITED
    Inventor: Yasuhiko Maki
  • Patent number: 6501694
    Abstract: Precharge circuits comprises PMOS transistors Q6 and Q7 each connected between a bit line and a power source potential VDD, PMOS transistors Q2, Q5, Q8 and Q11 connected between respective bit line pairs, and PMOS transistors Q21 and Q23 connected between respective adjacent bit lines of adjacent bit line pairs, wherein the gate electrodes of the PMOS transistors are each connected to a precharge control signal line PCG. The defect caused by omission of transistors from the prior art circuits is compensated by the PMOS transistors Q21 and Q23, each of which is required to be provided for two bit line pairs. With this and transistors of adjacent unit precharge circuits are arranged in plain symmetry, there is no need to provide transistors to be directly connected between bit lines *B2 and B3, and an average number of PMOS transistors for each bit line pair is less than 2.5.
    Type: Grant
    Filed: October 10, 2001
    Date of Patent: December 31, 2002
    Assignee: Fujitsu Limited
    Inventor: Yasuhiko Maki
  • Publication number: 20020191446
    Abstract: A semiconductor memory device includes a data access path for accessing a memory cell, a signal drive circuit which drives a signal on said data access path, a dummy path that emulates said data access path, and a dummy drive circuit which emulates said signal drive circuit, wherein said dummy path has a smaller load than said data access path, and said dummy drive circuit has a smaller drive capacity than said signal drive circuit.
    Type: Application
    Filed: March 22, 2002
    Publication date: December 19, 2002
    Applicant: FUJITSU LIMITED
    Inventor: Yasuhiko Maki
  • Publication number: 20020126555
    Abstract: Precharge circuits comprises PMOS transistors Q6 and Q7 each connected between a bit line and a power source potential VDD, PMOS transistors Q2, Q5, Q8 and Q11 connected between respective bit line pairs, and PMOS transistors Q21 and Q23 connected between respective adjacent bit lines of adjacent bit line pairs, wherein the gate electrodes of the PMOS transistors are each connected to a precharge control signal line PCG. The defect caused by omission of transistors from the prior art circuits is compensated by the PMOS transistors Q21 and Q23, each of which is required to be provided for two bit line pairs. With this and transistors of adjacent unit precharge circuits are arranged in plain symmetry, there is no need to provide transistors to be directly connected between bit lines *B2 and B3, and an average number of PMOS transistors for each bit line pair is less than 2.5.
    Type: Application
    Filed: October 10, 2001
    Publication date: September 12, 2002
    Applicant: FUJITSU LIMITED
    Inventor: Yasuhiko Maki
  • Patent number: 6239647
    Abstract: A decoder circuit includes a detecting device which detects a selecting signal for selecting the decoder circuit, a clock-signal supplying device which supplies a clock signal, and a decoded signal outputting device which outputs a decoded signal according to timing of the clock signal when the detecting device detects the selecting signal.
    Type: Grant
    Filed: November 16, 1999
    Date of Patent: May 29, 2001
    Assignee: Fujitsu Limited
    Inventors: Takako Kagiwata, Toshiyuki Uetake, Yasuhiko Maki
  • Patent number: 6081444
    Abstract: A static memory in which memory cells each have the components thereof laid out so that the area of each memory cell can be further reduced in compliance with improvement in technology of separating devices. The static memory includes CMOS memory cells each having two cross-coupled inverters, in each of which an n-channel transistor and p-channel transistor are connected in series with each other. At least one of the contacts used to cross-couple the two inverters is located in a region other than a region enclosed by the diffused sources and drains of the n-channel transistors and p-channel transistors included in the memory cell.
    Type: Grant
    Filed: December 3, 1998
    Date of Patent: June 27, 2000
    Assignee: Fujitsu Limited
    Inventors: Yasuhiko Maki, Hiroshi Shimizu, Hiroshi Kagiwata