Patents by Inventor Akihiro Iwase

Akihiro Iwase 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: 7474143
    Abstract: A voltage generator circuit which is capable of preventing the generation of a through current in a transition to a power-down mode to reduce current consumption. The voltage generator circuit includes a voltage generator activated by a reference voltage to generate an output voltage. A reference voltage clamp circuit is coupled to the voltage generator for clamping the reference voltage to a first voltage in response to a power-down signal to deactivate the voltage generator. An output voltage clamp circuit is coupled to the voltage generator for clamping the output voltage to a second voltage. A control circuit is coupled to the output voltage clamp circuit for enabling the output voltage clamp circuit after the voltage generator is deactivated in response to the power-down signal.
    Type: Grant
    Filed: July 6, 2006
    Date of Patent: January 6, 2009
    Assignee: Fujitsu Limited
    Inventors: Hajime Sato, Syuichi Saito, Akihiro Iwase
  • Patent number: 7330043
    Abstract: A multi-bus semiconductor device and a method of its probing test perform the DC test for individual pads of a device while dealing with an adequate number of devices for simultaneous measurement based on the scheme of input/output pad number compressive test. The semiconductor device includes switch elements SW0-SW4 connected between input/output pads P0-P4 and a testing line L0 so that pads in an arbitrary combination, among the off-probe pads P1-P4 that are not made in contact with the tester probe Pr0, are selected for testing in correspondence to the combination of switch elements that are turned on. The input/output buffers of the pads under test are deactivated to block their internal current paths. The corresponding switch elements are turned on to connect the off-probe pads under test to the probe pad P0 that is made in contact with the tester probe Pr0, and the leak current of the probes is measured with the tester TS.
    Type: Grant
    Filed: March 15, 2005
    Date of Patent: February 12, 2008
    Assignee: Fujitsu Limited
    Inventors: Seiji Yamamoto, Hirosuke Koumyoji, Tohru Yasuda, Mikio Ishikawa, Isaya Sobue, Hajime Sato, Chiaki Furukawa, Akira Sugiura, Akihiro Iwase
  • Publication number: 20060250176
    Abstract: A voltage generator circuit which is capable of preventing the generation of a through current in a transition to a power-down mode to reduce current consumption. The voltage generator circuit includes a voltage generator activated by a reference voltage to generate an output voltage. A reference voltage clamp circuit is coupled to the voltage generator for clamping the reference voltage to a first voltage in response to a power-down signal to deactivate the voltage generator. An output voltage clamp circuit is coupled to the voltage generator for clamping the output voltage to a second voltage. A control circuit is coupled to the output voltage clamp circuit for enabling the output voltage clamp circuit after the voltage generator is deactivated in response to the power-down signal.
    Type: Application
    Filed: July 6, 2006
    Publication date: November 9, 2006
    Inventors: Hajime Sato, Syuichi Saito, Akihiro Iwase
  • Patent number: 7095273
    Abstract: A voltage generator circuit which is capable of preventing the generation of a through current in a transition to a power-down mode to reduce current consumption. The voltage generator circuit includes a voltage generator activated by a reference voltage to generate an output voltage. A reference voltage clamp circuit is coupled to the voltage generator for clamping the reference voltage to a first voltage in response to a power-down signal to deactivate the voltage generator. An output voltage clamp circuit is coupled to the voltage generator for clamping the output voltage to a second voltage. A control circuit is coupled to the output voltage clamp circuit for enabling the output voltage clamp circuit after the voltage generator is deactivated in response to the power-down signal.
    Type: Grant
    Filed: February 4, 2002
    Date of Patent: August 22, 2006
    Assignee: Fujitsu Limited
    Inventors: Hajime Sato, Syuichi Saito, Akihiro Iwase
  • Publication number: 20050156589
    Abstract: A multi-bus semiconductor device and a method of its probing test perform the DC test for individual pads of a device while dealing with an adequate number of devices for simultaneous measurement based on the scheme of input/output pad number compressive test. The semiconductor device includes switch elements SW0-SW4 connected between input/output pads P0-P4 and a testing line L0 so that pads in an arbitrary combination, among the off-probe pads P1-P4 that are not made in contact with the tester probe Pr0, are selected for testing in correspondence to the combination of switch elements that are turned on. The input/output buffers of the pads under test are deactivated to block their internal current paths. The corresponding switch elements are turned on to connect the off-probe pads under test to the probe pad P0 that is made in contact with the tester probe Pr0, and the leak current of the probes is measured with the tester TS.
    Type: Application
    Filed: March 15, 2005
    Publication date: July 21, 2005
    Inventors: Seiji Yamamoto, Hirosuke Koumyoji, Tohru Yasuda, Mikio Ishikawa, Isaya Sobue, Hajime Sato, Chiaki Furukawa, Akira Sugiura, Akihiro Iwase
  • Patent number: 6885212
    Abstract: A multi-bus semiconductor device and a method of its probing test perform the DC test for individual pads of a device while dealing with an adequate number of devices for simultaneous measurement based on the scheme of input/output pad number compressive test. The semiconductor device includes switch elements SW0-SW4 connected between input/output pads P0-P4 and a testing line L0 so that pads in an arbitrary combination, among the off-probe pads P1-P4 that are not made in contact with the tester probe Pr0, are selected for testing in correspondence to the combination of switch elements that are turned on. The input/output buffers of the pads under test are deactivated to block their internal current paths. The corresponding switch elements are turned on to connect the off-probe pads under test to the probe pad P0 that is made in contact with the tester probe Pr0, and the leak current of the probes is measured with the tester TS.
    Type: Grant
    Filed: February 3, 2003
    Date of Patent: April 26, 2005
    Assignee: Fujitsu Limited
    Inventors: Seiji Yamamoto, Hirosuke Koumyoji, Tohru Yasuda, Mikio Ishikawa, Isaya Sobue, Hajime Sato, Chiaki Furukawa, Akira Sugiura, Akihiro Iwase
  • Patent number: 6762617
    Abstract: A semiconductor device has a normal operation mode and a test mode. A decision circuit determines whether the device has entered the test mode. A control circuit changes information related to the normal operation mode when a test mode has been entered. If the test mode is accidentally entered, then because the information related to normal operation has been changed, a user can readily determine that the device has entered the test mode.
    Type: Grant
    Filed: December 18, 2002
    Date of Patent: July 13, 2004
    Assignee: Fujitsu Limited
    Inventors: Akihiro Iwase, Yoshiharu Kato
  • Publication number: 20030234661
    Abstract: A multi-bus semiconductor device and a method of its probing test perform the DC test for individual pads of a device while dealing with an adequate number of devices for simultaneous measurement based on the scheme of input/output pad number compressive test. The semiconductor device includes switch elements SW0-SW4 connected between input/output pads P0-P4 and a testing line L0 so that pads in an arbitrary combination, among the off-probe pads P1-P4 that are not made in contact with the tester probe Pr0, are selected for testing in correspondence to the combination of switch elements that are turned on. The input/output buffers of the pads under test are deactivated to block their internal current paths. The corresponding switch elements are turned on to connect the off-probe pads under test to the probe pad P0 that is made in contact with the tester probe Pr0, and the leak current of the probes is measured with the tester TS.
    Type: Application
    Filed: February 3, 2003
    Publication date: December 25, 2003
    Applicant: Fujitsu Limited
    Inventors: Seiji Yamamoto, Hirosuke Koumyoji, Tohru Yasuda, Mikio Ishikawa, Isaya Sobue, Hajime Sato, Chiaki Furukawa, Akira Sugiura, Akihiro Iwase
  • Patent number: 6651196
    Abstract: A semiconductor device has a normal operation mode and a test mode. A decision circuit determines whether the device has entered the test mode. A control circuit changes information related to the normal operation mode when a test mode has been entered. If the test mode is accidentally entered, then because the information related to normal operation has been changed, a user can readily determine that the device has entered the test mode.
    Type: Grant
    Filed: February 15, 2000
    Date of Patent: November 18, 2003
    Assignee: Fujitsu Limited
    Inventors: Akihiro Iwase, Yoshiharu Kato
  • Publication number: 20030085731
    Abstract: A semiconductor device has a normal operation mode and a test mode. A decision circuit determines whether the device has entered the test mode. A control circuit changes information related to the normal operation mode when a test mode has been entered. If the test mode is accidentally entered, then because the information related to normal operation has been changed, a user can readily determine that the device has entered the test mode.
    Type: Application
    Filed: December 18, 2002
    Publication date: May 8, 2003
    Applicant: Fujitsu Limited
    Inventors: Akihiro Iwase, Yoshiharu Kato
  • Publication number: 20020167350
    Abstract: A voltage generator circuit which is capable of preventing the generation of a through current in a transition to a power-down mode to reduce current consumption. The voltage generator circuit includes a voltage generator activated by a reference voltage to generate an output voltage. A reference voltage clamp circuit is coupled to the voltage generator for clamping the reference voltage to a first voltage in response to a power-down signal to deactivate the voltage generator. An output voltage clamp circuit is coupled to the voltage generator for clamping the output voltage to a second voltage. A control circuit is coupled to the output voltage clamp circuit for enabling the output voltage clamp circuit after the voltage generator is deactivated in response to the power-down signal.
    Type: Application
    Filed: February 4, 2002
    Publication date: November 14, 2002
    Applicant: Fujitsu Limited
    Inventors: Hajime Sato, Syuichi Saito, Akihiro Iwase
  • Patent number: 5747837
    Abstract: A semiconductor device with an expanded range of a recommended condition for an input voltage is disclosed. In embodiment, the semiconductor device having input protection on an input terminal thereto, includes: a semiconductor region having a first conducting type, first and second diffusion regions defined in the semiconductor region and respectively having a second conducting type, and a transistor formed by using the semiconductor region as a base, the first diffusion region as a collector, and the second diffusion region as an emitter. The first diffusion region is connected to one of a high-potential power supply and a low-potential power supply, the second diffusion region is connected to the input terminal, and the semiconductor region is connected to another power supply having a voltage high enough to reverse bias the junction between the semiconductor region and the first diffusion region.
    Type: Grant
    Filed: December 10, 1996
    Date of Patent: May 5, 1998
    Assignee: Fujitsu Limited
    Inventors: Akihiro Iwase, Tomio Nakano, Teruo Seki
  • Patent number: 5719812
    Abstract: A semiconductor memory includes a power down pulse generating circuit having an output delay time which is dependent on the type of change or transition in an input signal. The pulse generating circuit generates a power down signal at different times depending on whether the input signal changes from a first level to a second level or from the second level to the first level to prevent the power down signal from being output twice when an input clock signal has a pulse width shorter than a normal pulse width thereof. The power down pulse generating circuit generates the power down signal in response to a signal from address transition detection circuitry, and causes data read/write circuitry and bit line pulse generating circuitry to become inactive to reduce power consumption. The bit line pulse generating circuitry generates reset signals which may be used to reset or precharge the bit lines at different timings to reduce peak current in the semiconductor memory.
    Type: Grant
    Filed: September 3, 1996
    Date of Patent: February 17, 1998
    Assignees: Fujitsu Limited, Fujitsu VLSI Ltd.
    Inventors: Teruo Seki, Akihiro Iwase, Shinzi Nagai
  • Patent number: 5631865
    Abstract: A semiconductor memory device includes a sense amplifier and a load circuit which are connected to a pair of data buses through which cell data is read. The sense amplifier produces an output data signal in accordance with voltage potentials of transfer signals on the data buses. During data reading operation of the memory device, the sense amplifier is enabled and the transfer signals on the data buses have a different voltage potential level from each other. The load circuit sets the data buses at a predetermined reset voltage potential in a stand by state of the data reading operation. The reset voltage potential is intermediate of the voltage potential levels of the data buses when the sense amplifier is enabled.
    Type: Grant
    Filed: November 27, 1995
    Date of Patent: May 20, 1997
    Assignee: Fujitsu Limited
    Inventors: Akihiro Iwase, Masaharu Kagohashi
  • Patent number: 5475639
    Abstract: Disclosed is a semiconductor memory device which operates based on voltages from a high voltage power source and a low voltage power source. A plurality of memory cells are formed in a memory cell array. Plural pairs of bit lines are connected to the memory cells to transfer data signals read from the memory cells. A sense amplifier, which has a pair of input terminals, amplifies the data signal. A level shifter is selectively connected to plural pairs of bit lines to shift the level of the data signal of a selected pair of bit lines to a level near the operation point of the sense amplifier, and supplies a resultant data signal to the sense amplifier. The level shifter includes a first transistor for receiving the data signal, and a plurality of second transistors connected between the first transistor and the low voltage power source.
    Type: Grant
    Filed: March 21, 1994
    Date of Patent: December 12, 1995
    Assignees: Fujitsu Limited, Fujitsu VLSI Limited
    Inventors: Akihiro Iwase, Teruo Seki, Shinji Nagai, Tadashi Ozawa
  • Patent number: 5453956
    Abstract: A load generator is disclosed, which controls the voltage swing of the complementary logic signals generated in a semiconductor memory device. The load generator includes a first load circuit for controlling the potential levels of the signals appearing on a pair of complementary input signal lines. The first load circuit includes a first and second voltage dividers connected to the complementary input signal lines. Each of the first and second voltage dividers include a first voltage dividing transistor and a first voltage dividing resistive element connected in series between the semiconductor's low and high potential power supplies. The two first voltage dividing transistors are connected to each other in such a manner that a voltage, divided by one of the two transistors, is applied to the gate of the other transistor. The load generator further includes a second load circuit for controlling the potential levels of the signals appearing on a pair of complementary output signal lines.
    Type: Grant
    Filed: February 1, 1995
    Date of Patent: September 26, 1995
    Assignees: Fujitsu Limited, Fujitsu VLSI Limited
    Inventors: Akihiro Iwase, Teruo Seki, Masaharu Kagohashi
  • Patent number: 5097159
    Abstract: A delay circuit having two or more first switching transistors connected in series between an output terminal and a power source line, and two or more second switching transistors connected in series between the output terminal and another power source line, the first and the second switching transistors operating in a complementary manner in response to an input signal, one or more nodes of each switching transistor being connected by one or more current paths each connecting at least one capacitor, whereby an input signal is transmitted to the output terminal at a specified interval defined by the capacitance of the capacitor.
    Type: Grant
    Filed: February 21, 1989
    Date of Patent: March 17, 1992
    Assignees: Fujitsu Limited, Fujitsu VLSI Limited
    Inventors: Teruo Seki, Akihiro Iwase, Sinzi Nagai