Patents by Inventor Tsuyoshi Ohira
Tsuyoshi Ohira 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).
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Patent number: 4870617Abstract: A semiconductor memory device comprises a plurality of reset circuits connected to a data bus pair at different locations. Before each read operation, the reset circuits reset the data bus pair to a predetermined reset voltage. The resetting of the data bus pair is virtually unaffected by the distributed resistances and parasitic capacitances of the data bus pair, since the resetting is carried out at a plurality of locations on the data bus pair.Type: GrantFiled: September 16, 1987Date of Patent: September 26, 1989Assignees: Fujitsu Limited, Fujitsu Vlsi LimitedInventors: Masao Nakano, Tsuyoshi Ohira, Hirohiko Mochizuki, Yukinori Kodama, Hidenori Nomura
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Patent number: 4821232Abstract: A semiconductor memory device comprises a memory cell array comprising a plurality of memory cells arranged in a matrix arrangement, a sense amplifier, operatively connected to the memory cell array, amplifying a signal read out from one of the memory cells and having a pair of output terminals for outputting a complementary signal, a pair of data buses for transferring the complementary signal, a transfer gate for connecting the pair of output terminals to the pair of data buses responsive to a read operation, a data output buffer connected to the pair of data buses for outputting an output signal, and a reset circuit for resetting the pair of data buses to a predetermined voltage before each read operation responsive to a reset clock signal.Type: GrantFiled: September 16, 1987Date of Patent: April 11, 1989Assignees: Fujitsu Limited, Fujitsu VLSI LimitedInventors: Masao Nakano, Tsuyoshi Ohira, Hirohiko Mochizuki, Yukinori Kodama, Hidenori Nomura
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Patent number: 4806795Abstract: A transfer gate circuit including a first MIS transistor which transmits an input signal supplied from an input side thereof to an output side thereof in accordance with a control signal supplied to a gate of the first MIS transistor; an inverter circuit connected between power supply lines which inverts the potential of the transmitted input signal; and an output level guarantee circuit comprising second and third MIS transistors which have conductivity type opposite to that of the first MIS transistor and are connected in series between one of the power supply lines and the output side, an output signal of the inverter circuit being supplied to a gate of the second MIS transistor, an inverted signal of the control signal supplied to the gate of the first MIS transistor being supplied to a gate of the third MIS transistor.Type: GrantFiled: September 16, 1987Date of Patent: February 21, 1989Assignees: Fujitsu Limited, Fujitsu Vlsi LimitedInventors: Masao Nakano, Tsuyoshi Ohira, Hidenori Nomura
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Patent number: 4807192Abstract: A memory device employing address multiplexing comprises a counter. An external address is initially set in the counter and a counter address value is incremented responsive to toggle of a column address strobe. The counted address value in the counter is supplied as an address signal directly to a column decoder or indirectly to the column decoder through an address buffer. The memory device may be provided with a switching logic circuit which switches the address bits in the counter depending on switching information so that it is possible to arbitrarily determine which address bits in the counter are to determine a nibble address.Type: GrantFiled: August 31, 1987Date of Patent: February 21, 1989Assignees: Fujitsu Limited, Fujitsu Vlsi LimitedInventors: Masao Nakano, Hirohiko Mochizuki, Tsuyoshi Ohira, Yukinori Kodama, Hidenori Nomura
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Patent number: 4799197Abstract: A semiconductor memory device comprises a memory cell array comprising memory cells; a plurality of pairs of bit lines which are coupled to the memory cells and a data bus, each bit line being divided into at least two pairs of bit line parts; at least one sense amplifier provided between the pairs of bit line parts in each of the pairs of bit lines, for sensing a difference in potential between bit line parts in each pair, the sense amplifier being formed with complementary metal oxide semiconductor transistors; and at least a pair of transfer gates provided between a non-data bus side and a data bus side of the sense amplifier, the pair of transfer gates being held in an off-state when the sense amplifier is activated.Type: GrantFiled: September 1, 1987Date of Patent: January 17, 1989Assignees: Fujitsu Limited, Fujitsu VLSI LimitedInventors: Yukinori Kodama, Hirohiko Mochizuki, Masao Nakano, Tsuyoshi Ohira, Hidenori Nomura
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Patent number: 4583204Abstract: A dynamic semiconductor memory device includes data output lines (D, D), a data output buffer (12), a column enable buffer (9), and an output enable buffer (11) for generating an output enable signal (OE) to enable the transmission of data from the data output lines to the data buffer. The output enable buffer is driven by the clock signals of the column enable buffer. An output disabling circuit (13) is provided to stop the generation of an output enable signal by the output enable buffer when the output enable buffer is not being driven by the column enable buffer. As a result, the data output buffer assumes a high-impedance state when a power supply is turned on.Type: GrantFiled: December 23, 1982Date of Patent: April 15, 1986Assignee: Fujitsu LimitedInventors: Yoshihiro Takemae, Shigeki Nozaki, Tsuyoshi Ohira
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Patent number: 4550289Abstract: A semiconductor integrated circuit (IC) device includes therein a test circuit. The test circuit operates to distinguish the power source level during the testing or ground level occurring at an internal node located inside the semiconductor chip. The test circuit includes a series-connected MIS transistor and an MIS diode. The gate of the MIS transistor is connected to the internal node. The MIS diode is connected to an external input/output (I/O) pin. The level at the internal node, i.e., the power source level or the ground level, can be distinguished by a first voltage level or a second voltage level applied to the external I/O pin, whichever enables a current to be drawn from the external I/O pin.Type: GrantFiled: December 27, 1982Date of Patent: October 29, 1985Assignee: Fujitsu LimitedInventors: Katsuhiko Kabashima, Yoshihiro Takemae, Shigeki Nozaki, Tsuyoshi Ohira, Hatsuo Miyahara, Masakazu Kanai, Seiji Enomoto
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Patent number: 4532613Abstract: In a semiconductor memory device including an output buffer circuit receiving data signals read out from a memory cell array, an output stage MOS transistor being turned ON and OFF according to the output signals of the output buffer circuit, and an output buffer enable (OBE) signal generator circuit for generating an OBE signal which is used as the voltage supply to the output stage of the output buffer circuit, a V.sub.BS voltage generator circuit is provided for generating a voltage V.sub.BS higher than the voltage source V.sub.CC preceding the rising up of the OBE signal, which voltage V.sub.BS is used as a voltage supply to the output stage of the OBE signal generator circuit, whereby the OBE signal is formed as a voltage waveform which rises rapidly up to a level higher than the voltage source V.sub.CC.Type: GrantFiled: March 9, 1982Date of Patent: July 30, 1985Assignee: Fujitsu LimitedInventors: Yoshihiro Takemae, Tomio Nakano, Tsuyoshi Ohira
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Patent number: 4504929Abstract: A dynamic semiconductor memory device provides a selected real cell, which is connected to a first of a pair of bit lines connected to a sense amplifier, and a dummy cell which is connected to a second of the pair of bit lines so as to perform a read-out operation. The dynamic semiconductor memory cell further provides an active restore circuit for pulling up the bit line potential of the bit line on the higher potential side of the pair of bit lines, in which the potential difference is increased by the read-out operation. The dynamic semiconductor cell can also provide a write-in circuit for charging the selected real cell through the bit line. A test power source pad is provided in the active restore circuit or the write in circuit so that when the reference level of the real cell is tested an optional power source can be applied from the test power source pad instead of from a normal power source.Type: GrantFiled: November 24, 1982Date of Patent: March 12, 1985Assignee: Fujitsu LimitedInventors: Yoshihiro Takemae, Tsuyoshi Ohira, Seiji Enomoto
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Patent number: 4484312Abstract: A dynamic random access memory device which comprises one-transistor, one-capacitor-type memory cells (C.sub.00 .about.C.sub.127,127) in rows and columns and dummy cells (DC.sub.20 '.about.DC.sub.2,127 ', DC.sub.20 ".about.DC.sub.2,127 ", DC.sub.20 "'.about.DC.sub.2,127 "') in rows. The capacitors (C.sub.d) of the dummy cells are charged to a high power supply potential (V.sub.CC) by one or more charging transistors (Q.sub.A or Q.sub.A ') clocked by a reset clock signal (.phi..sub.R). The capacitors (C.sub.d) of the dummy cells are discharged to a low power supply potential (V.sub.SS) by one or more transistors (Q.sub.B or Q.sub.B ') clocked by an operation clock signal (.phi..sub.WL) having a potential lower than the high power supply potential (V.sub.CC).Type: GrantFiled: June 25, 1982Date of Patent: November 20, 1984Assignee: Fujitsu LimitedInventors: Tomio Nakano, Masao Nakano, Yoshihiro Takemae, Norihisa Tsuge, Tsuyoshi Ohira
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Patent number: 4450515Abstract: A bias-voltage generator suitable for measuring a substrate leakage current is disclosed. The bias-voltage generator comprises of an oscillator, a charge-pumping circuit which is driven by the oscillator via a pumping capacitor, and a charge-pumping switch. The charge-pumping switch is connected in series with the charge-pumping circuit. The charge-pumping switch cooperates with an external electrode for controlling the ON or OFF condition of the charge pumping circuit. The charge-pumping switch is turned OFF by the external electrode becoming a floating state and a resistor employed to ensure the charge pumping switch is inoperable after the above-mentioned measurement is completed and the circuit is shipped from the factory.Type: GrantFiled: June 14, 1982Date of Patent: May 22, 1984Assignee: Fujitsu LimitedInventors: Yoshihiro Takemae, Tomio Nakano, Masao Nakano, Norihisa Tsuge, Tsuyoshi Ohira