Patents by Inventor Akihiro Hirota

Akihiro Hirota 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).

  • Publication number: 20110187446
    Abstract: A semiconductor device includes a bonding option pad, an internal power supply, and a MOS transistor. The bonding option pad is selectively wire-bonded to two voltage supply portions through which external power supply voltages with different power supply potentials are supplied from an external power supply. The internal power supply is caused to generate a pre-specified internal power supply voltage. The MOS transistor stabilizes an output level of the internal power supply voltage. The source and drain of the MOS transistor are shorted together and connected to the bonding option pad, and the gate there.
    Type: Application
    Filed: January 18, 2011
    Publication date: August 4, 2011
    Applicant: OKI SEMICONDUCTOR CO., LTD.
    Inventor: Akihiro Hirota
  • Publication number: 20110185239
    Abstract: The present invention provides a semiconductor testing apparatus and method capable of reliably determining whether a semiconductor memory is good or bad. A “1” reading test of each cell corresponding to one bit at a first step is first performed on a memory cell array. “0” writing of each cell corresponding to one bit at a second step and a “0” reading test of each cell corresponding to one bit at a third step are executed on the memory cell array. Thus, the time taken from the supply of power to the start of the “0” reading test of the reference cell at the third step can be significantly shortened. As a result, a defect of a reference bit line due to a breaking or high resistance of a gate of a reference column switch transistor corresponding to a normally ON transistor can be screened.
    Type: Application
    Filed: April 6, 2011
    Publication date: July 28, 2011
    Applicant: OKI SEMICONDUCTOR CO., LTD.
    Inventor: Akihiro HIROTA
  • Publication number: 20110181329
    Abstract: An internal pulse waveform shaping circuit provided to an IC chip generates an internal pulse monitor signal that changes in a predetermined direction at a rise timing of an internal pulse signal during a period in which a first enable signal is asserted and a second enable signal is de-asserted and then continues in the changed state for a predetermined period of time or longer, and generates the internal pulse monitor signal that changes in the predetermined direction at a fall timing of the pulse signal during a period in which the first enable signal is de-asserted and the second enable signal is asserted and then continues in the changed state for the predetermined period of time or longer. The generated internal pulse monitor signal is output to a tester for detecting the pulse width of the internal pulse signal.
    Type: Application
    Filed: January 25, 2011
    Publication date: July 28, 2011
    Applicant: OKI SEMICONDUCTOR CO., LTD.
    Inventor: Akihiro Hirota
  • Patent number: 7965065
    Abstract: A trimming circuit which comprises a shunt circuit having two shunt resistors and two shunt ON/OFF switches and connected in parallel with a series resistor circuit. The middle point of the shunt circuit is connected to a connection point of the series resistor circuit, the resistance ratio thereof with respect to the connection point being equal to the resistance ratio of the shunt resistors.
    Type: Grant
    Filed: July 16, 2008
    Date of Patent: June 21, 2011
    Assignee: Oki Semiconductor Co., Ltd.
    Inventor: Akihiro Hirota
  • Publication number: 20100246283
    Abstract: There is provided a reference potential generating circuit of a semiconductor memory, including: a first MOS transistor group that includes a plurality of first MOS transistors that are connected in series; a second MOS transistor that is connected in series to the first MOS transistor group; a third MOS transistor that is connected in parallel to the circuit in which the first MOS transistor group and the second MOS transistor are connected in series, has a gate connected to a connection point of the first MOS transistor group and the second MOS transistor, and corrects a reference potential from a connection point of the first MOS transistors; and a fourth MOS transistor that is connected to the gate of the third MOS transistor, and decreases the potential of the gate of the third MOS transistor when a permission signal to supply power to the semiconductor memory is input.
    Type: Application
    Filed: March 24, 2010
    Publication date: September 30, 2010
    Applicant: OKI SEMICONDUCTOR CO., LTD.
    Inventor: Akihiro Hirota
  • Publication number: 20100246306
    Abstract: There is provided a start-up circuit of an internal power supply of a semiconductor memory, including: an odd number of inverters that are connected in series and output a signal indicating whether or not to start to supply power from an internal power supply circuit of the semiconductor memory to an internal power supply circuit, and a discharge unit that is connected to an output side of an inverter at an odd-numbered stage and discharges charges remaining at the connection point between the inverter at the odd-numbered stage and the inverter at the stage immediately thereafter, after supply of power to operate the inverters is stopped.
    Type: Application
    Filed: March 22, 2010
    Publication date: September 30, 2010
    Applicant: OKI SEMICONDUCTOR CO., LTD.
    Inventor: Akihiro Hirota
  • Publication number: 20100246307
    Abstract: An internal power supply control circuit of a semiconductor memory includes a periodic signal generating unit that generates a periodic signal to generate a permission signal to intermittently permit supply of power from an internal power supply circuit of the semiconductor memory to an internal circuit thereof with a predetermined period, when a mode changes from a normal operation mode where power is always supplied from the internal power supply circuit to the internal circuit to a standby mode where consumption power is further suppressed as compared with consumption power in the normal operation mode, and a permission signal output unit that outputs the permission signal synchronized with the periodic signal to the internal power supply circuit, when a mode signal indicating any mode of the normal operation mode and the standby mode and the periodic signal are input and the input mode signal indicates the standby mode.
    Type: Application
    Filed: March 22, 2010
    Publication date: September 30, 2010
    Applicant: OKI SEMICONDUCTOR CO., LTD.
    Inventor: Akihiro Hirota
  • Publication number: 20090089633
    Abstract: The present invention provides a semiconductor testing apparatus and method capable of reliably determining whether a semiconductor memory is good or bad. A “1” reading test of each cell corresponding to one bit at a first step is first performed on a memory cell array. “0” writing of each cell corresponding to one bit at a second step and a “0” reading test of each cell corresponding to one bit at a third step are executed on the memory cell array. Thus, the time taken from the supply of power to the start of the “0” reading test of the reference cell at the third step can be significantly shortened. As a result, a defect of a reference bit line due to a breaking or high resistance of a gate of a reference column switch transistor corresponding to a normally ON transistor can be screened.
    Type: Application
    Filed: August 22, 2008
    Publication date: April 2, 2009
    Applicant: OKI ELECTRIC INDUSTRY CO., LTD.
    Inventor: Akihiro HIROTA
  • Publication number: 20090072804
    Abstract: A trimming circuit which comprises a shunt circuit having two shunt resistors and two shunt ON/OFF switches and connected in parallel with a series resistor circuit. The middle point of the shunt circuit is connected to a connection point of the series resistor circuit, the resistance ratio thereof with respect to the connection point being equal to the resistance ratio of the shunt resistors.
    Type: Application
    Filed: July 16, 2008
    Publication date: March 19, 2009
    Applicant: OKI ELECTRIC INDUSTRY CO., LTD.
    Inventor: Akihiro HIROTA
  • Publication number: 20090072893
    Abstract: A voltage supply circuit which conducts a current from a power supply into a current supply line comprises a plurality of current drive circuits connected in parallel to the current supply line each of which conducts current from the power supply into the current supply line. Different reference voltages are respectively given to the plurality of current drive circuits, each of which compares a comparison voltage corresponding to a generated voltage developed across load resistors with the respective reference voltage and, when the comparison voltage exceeds the respective reference voltage, stops supplying current.
    Type: Application
    Filed: July 18, 2008
    Publication date: March 19, 2009
    Applicant: OKI ELECTRIC INDUSTRY CO., LTD.
    Inventor: Akihiro Hirota
  • Patent number: 6791894
    Abstract: A power-source controller for reducing current consumption while a DRAM is in standby, includes a mode detection circuit inverting a disable signal having an L-level under the enable state and having an H-level under the disable state; an internal-power-source driver circuit having first and second transistors; and an internal-power-source reference circuit setting first and second driver control signals respectively to L-level and H-level when an L-level disable signal is input to turn on the first transistor and turn off the second transistor, supplying an external-power-source voltage as an internal-power-source voltage, setting the first driver control signal to H-level when an H-level disable signal is input, controlling the level of the second driver control signal to turn off the second transistor and control the first transistor, and supplying an internal power-source voltage lower than the external-power-source voltage.
    Type: Grant
    Filed: September 23, 2002
    Date of Patent: September 14, 2004
    Assignee: Oki Electric Industry Co., Ltd.
    Inventors: Wataru Nagai, Akihiro Hirota, Junichi Suyama
  • Publication number: 20030151967
    Abstract: To provide a power-source controller for reducing the current consumption while a DRAM is standby. The power-source controller is constituted by a mode detection circuit 4 for inverting an L-level disable signal under the enable state and inverting a disable signal into H-level under the disable state, an internal-power-source driver circuit 6 having Pch-Tr 6a and Pch-Tr 6b, and an internal-power-source reference circuit 5 for setting a first driver control signal to L-level and a second driver control signal to H-level when an L-level disable signal is input to turn on Pch-Tr 6b and turn off Pch-Tr 6a, supplying an external-power-source voltage VCC as an internal-power-source voltage IVC, setting a first driver control signal to H-level when an H-level disable signal is input, controlling the level of a second driver control signal to turn off Pch-Tr 6b and control Pch-Tr 6a, and supplying an internal power-source voltage IVC1 lower than the external-power-source voltage VCC.
    Type: Application
    Filed: September 23, 2002
    Publication date: August 14, 2003
    Inventors: Wataru Nagai, Akihiro Hirota, Junichi Suyama
  • Patent number: 6574150
    Abstract: A low power consumption type dynamic random access memory (DRAM) operable with reduced current consumption responsive to an external signal, without causing occurrence of malfunction during low current consumption. An input circuit for receiving signals, a memory array for holding data, and a peripheral circuit for controlling the memory array are driven by an internal voltage supplied by two groups of internal voltage receiving circuits, while an output circuit for outputting signals is driven by an external power supply. The two groups of internal voltage receiving circuits are deactivated in response to an externally provided power supply control signal, and the output circuit is controlled so as to be in a high impedance condition with voltage of the external power supply being applied thereto.
    Type: Grant
    Filed: June 21, 2002
    Date of Patent: June 3, 2003
    Assignee: Oki Electric Industry Co., Ltd.
    Inventors: Junichi Suyama, Wataru Nagai, Akihiro Hirota, Shota Ohtsubo
  • Publication number: 20020163847
    Abstract: There provides a low power consumption type dynamic random access memory (DRAM) with reduced current consumption in the DRAM by a signal from outside and without causing occurrence of malfunction at times of low current consumption. An input circuit for receiving signals, a memory array for holding data, and a peripheral circuit for controlling the memory array are driven by an internal voltage supplied by two groups of internal voltage receiving circuits while an output circuit for outputting signals is driven by an external power supply. The two groups of internal voltage receiving circuits are deactivated in response to a power supply control signal CONT inputted from outside, and the output circuit is controlled so as to be in a high impedance condition with voltage of the external power supply being applied thereto.
    Type: Application
    Filed: June 21, 2002
    Publication date: November 7, 2002
    Inventors: Junichi Suyama, Wataru Nagai, Akihiro Hirota, Shota Ohtsubo
  • Patent number: 6438061
    Abstract: There provides a low power consumption type dynamic random access memory (DRAM) with reduced current consumption in the DRAM by a signal from outside and without causing occurrence of malfunction at times of low current consumption. An input circuit for receiving signals, a memory array for holding data, and a peripheral circuit for controlling the memory array are driven by an internal voltage supplied by two groups of internal voltage receiving circuits while an output circuit for outputting signals is driven by an external power supply. The two groups of internal voltage receiving circuits are deactivated in response to a power supply control signal CONT inputted from outside, and the output circuit is controlled so as to be in a high impedance condition with voltage of the external power supply being applied thereto.
    Type: Grant
    Filed: July 18, 2001
    Date of Patent: August 20, 2002
    Assignee: Oki Electric Industry Co., Ltd.
    Inventors: Junichi Suyama, Wataru Nagai, Akihiro Hirota, Shota Ohtsubo
  • Publication number: 20020021612
    Abstract: There provides a low power consumption type dynamic random access memory (DRAM) with reduced current consumption in the DRAM by a signal from outside and without causing occurrence of malfunction at times of low current consumption. An input circuit for receiving signals, a memory array for holding data, and a peripheral circuit for controlling the memory array are driven by an internal voltage supplied by two groups of internal voltage receiving circuits while an output circuit for outputting signals is driven by an external power supply. The two groups of internal voltage receiving circuits are deactivated in response to a power supply control signal CONT inputted from outside, and the output circuit is controlled so as to be in a high impedance condition with voltage of the external power supply being applied thereto.
    Type: Application
    Filed: July 18, 2001
    Publication date: February 21, 2002
    Inventors: Junichi Suyama, Wataru Nagai, Akihiro Hirota, Shota Ohtsubo
  • Patent number: 5949729
    Abstract: A sense circuit for a DRAM circuit in which small potential difference between bit lines and is produced when the memory cell in the memory cell array is connected to one of the bit lines. The sense circuit starts sensing and amplifying when the sense starting signal changes to "L" level. An inverter provides a sense activating signal of "H" level to an NMOS device, while another inverter provides a sense activating signal of "L" level to a PMOS device. Sense amplifiers 33 are then activated and the potential difference between the bit lines and is amplified. Since the "L" level of the sense activating signal that is generated by the inverter is set to a value midway between a first power potential VSS and a second power potential VCC, the conductive resistance of the PMOS device is higher than that of a conventional circuit supplied with the first power potential VSS. Consequently, the voltage drop due to the PMOS device increases and power noise is reduced.
    Type: Grant
    Filed: July 21, 1997
    Date of Patent: September 7, 1999
    Assignee: Oki Electric Industry Co., Ltd.
    Inventors: Junichi Suyama, Kazukiyo Fukudome, Akihiro Hirota