Patents by Inventor Takesada Akiba
Takesada Akiba 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: 5995404Abstract: A DRAM memory device has bond pads, such as DQa through DQh, arranged along the length of the substrate in a certain order. The bond pads carry data signals to and from the device with each bond pad carrying the same data bit of every data word. Arrays of memory cells 1201, 1210 extend transverse of the bond pads and are arranged in pairs of columns 1212-1226. Data circuits 1242, 1244 transmit the data signals between the bond pads and arrays. The data circuits include data lines 1230-1236 extending between the bond pads and pairs of columns of arrays. Each data line extends from one bond pad to plural pairs of columns of arrays in a sequence the same certain order.Type: GrantFiled: July 11, 1997Date of Patent: November 30, 1999Assignee: Texas Instruments IncorporatedInventors: Masayuki Nakaumura, Brent S. Haukness, Takesada Akiba
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Patent number: 5966341Abstract: A semiconductor memory such as a dynamic RAM having memory mats each divided into a plurality of units or sub-memory mats. Each sub-memory mat comprises: a memory array having sub-word lines and sub-bit lines intersecting orthogonally and dynamic memory cells located in lattice fashion at the intersection points between the intersecting sub-word and sub-bit lines; a sub-word line driver including unit sub-word line driving circuits corresponding to the sub-word lines; a sense amplifier including unit amplifier circuits and column selection switches corresponding to the sub-bit lines; and sub-common I/O lines to which designated sub-bit lines are connected selectively via the column selection switches. The sub-memory mats are arranged in lattice fashion.Type: GrantFiled: December 2, 1997Date of Patent: October 12, 1999Assignees: Hitachi, Ltd., Hitachi Device Engineering Co. Ltd.Inventors: Tsugio Takahashi, Goro Kitsukawa, Takesada Akiba, Yasushi Kawase, Masayuki Nakamura
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Patent number: 5953242Abstract: A method and apparatus for providing a meshed power and signal bus system on an array type integrated circuit that minimizes the size of the circuit. In a departure from the art, through-holes for the mesh system are placed in the cell array, as well as the peripheral circuits. The power and signal buses of the mesh system run in both vertical and horizontal directions across the array such that all the vertical buses lie in one metal layer, and all the horizontal buses lie in another metal layer. The buses of one layer are connected to the appropriate bus(es) of the other layer using through-holes located in the array. Once connected, the buses extend to the appropriate sense amplifier drivers. The method and apparatus are facilitated by an improved subdecoder circuit implementing a hierarchical word line structure.Type: GrantFiled: December 16, 1997Date of Patent: September 14, 1999Assignees: Hitachi Ltd., Texas Instruments IncorporatedInventors: Goro Kitsukawa, Takesada Akiba, Hiroshi Otori, William R. McKee, Jeffrey E. Koelling, Troy H. Herndon
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Patent number: 5881005Abstract: The present invention is a method and apparatus for overdriving signals received by a sense amplifier circuit. To this end, an overdrive circuit comprising an n-channel common source switch drives the signal to be sensed for a period of time to a voltage level greater than a normal level. The period of time the signal is overdriven corresponds to the operating voltage of the sense amplifier circuit. Upon completion of the overdriving, a normalization circuit drives the signal to be sensed for a second period of time to the normal level, thereby preparing it for the next memory cycle so that the signals can be once again set to the desired precharge level.Type: GrantFiled: January 13, 1997Date of Patent: March 9, 1999Assignee: Hitachi, Ltd.Inventors: Hiroshi Otori, Takesada Akiba
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Patent number: 5859807Abstract: The present invention is a method and apparatus for overdriving signals received by a sense amplifier circuit. To this end, an overdrive circuit drives the signal to be sensed for a period of time to a voltage level greater than a normal level. The length of the period of time corresponds to the location of the sense amplifier circuit relative to a sense enabling circuit. Upon completion of the overdriving, a normalization circuit drives the signal to be sensed for a second period of time to the normal level, thereby preparing it for the next memory cycle so that the signals can be once again set to a desired precharge level.Type: GrantFiled: April 24, 1997Date of Patent: January 12, 1999Assignee: Hitachi, Ltd.Inventors: Hiroshi Otori, Takesada Akiba, Goro Kitsukawa, Hugh McAdams
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Patent number: 5844853Abstract: A circuit and method for providing a plurality of voltage regulators whose outputs are constant for ranges of different external voltages are disclosed. The voltage regulators are made to be adaptable to two different ranges of external voltages through use of a master-slice technique. Furthermore, in a first voltage regulator, the supply current capability of the regulator is significantly increased under very low external voltage conditions. In a second voltage regulator, the voltage level on any node of the regulator does not exceed a voltage level that is too high, yet still sinks most of its current from the external power supply. A third voltage regulator is able to charge and discharge its output voltage so that it will maintain at a constant level. Finally, a fourth voltage regulator is optimized to reduce dielectric leakage.Type: GrantFiled: January 29, 1997Date of Patent: December 1, 1998Assignees: Texas Instruments, Inc., Hitachi, Ltd.Inventors: Goro Kitsukawa, Wah Kit Loh, Takesada Akiba, Masayuki Nakamura, Hiroshi Otori
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Patent number: 5793694Abstract: The present invention is a method and apparatus for reducing the peak current for all the bit mats during a CAS-before-RAs refresh operation of a DRAM. To this end, a circuit is created to detect a CAS-before-RAS refresh operation. When a CBR refresh is detected, the amplifying of the bit mats are offset from each other, thereby staggering the time when each bit mat draws its peak current. In an alternative embodiment, when a CBR refresh is detected, the activation of the word lines are offset from each other, thereby staggering the time when each bit mat draws its peak current.Type: GrantFiled: December 17, 1996Date of Patent: August 11, 1998Assignee: Hitachi, Ltd.Inventors: Takesada Akiba, Hiroshi Otori, Masayuki Nakamura, Adin Hyslop
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Patent number: 5777927Abstract: A semiconductor memory such as a dynamic RAM having memory mats each divided into a plurality of units or sub-memory mats. Each sub-memory mat comprises: a memory array having sub-word lines and sub-bit lines intersecting orthogonally and dynamic memory cells located in lattice fashion at the intersection points between the intersecting sub-word and sub-bit lines; a sub-word line driver including unit sub-word line driving circuits corresponding to the sub-word lines; a sense amplifier including unit amplifier circuits and column selection switches corresponding to the sub-bit lines; and sub-common I/O lines to which designated sub-bit lines are connected selectively via the column selection switches. The sub-memory mats are arranged in lattice fashion.Type: GrantFiled: January 7, 1997Date of Patent: July 7, 1998Assignees: Hitachi, Ltd., Hitachi Device Engineering Co., Ltd.Inventors: Tsugio Takahashi, Goro Kitsukawa, Takesada Akiba, Yasushi Kawase, Masayuki Nakamura
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Patent number: 5703825Abstract: A circuit and method for reducing the leakage current drawn by a transistor when it is inactive. In a first implementation, a circuit selectively drives the gate of a transistor to a voltage level above a source voltage. As a result, the gate-source voltage is reversed and the leakage current flowing through the transistor is substantially reduced. In a second implementation, a circuit selectively biases the well of a transistor to a voltage level above a normal bias voltage. As a result, the voltage-current characteristics of the transistor are modified so that the leakage current is substantially eliminated.Type: GrantFiled: January 23, 1997Date of Patent: December 30, 1997Assignee: Hitachi Ltd.Inventors: Takesada Akiba, Goro Kitsukawa
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Patent number: 5604697Abstract: A semiconductor memory such as a dynamic RAM having memory mats each divided into a plurality of units or sub-memory mats. Each sub-memory mat comprises: a memory array having sub-word lines and sub-bit lines intersecting orthogonally and dynamic memory cells located in lattice fashion at the intersection points between the intersecting sub-word and sub-bit lines; a sub-word line driver including unit sub-word line driving circuits corresponding to the sub-word lines; a sense amplifier including unit amplifier circuits and column selection switches corresponding to the sub-bit lines; and sub-common I/O lines to which designated sub-bit lines are connected selectively via the column selection switches. The sub-memory mats are arranged in lattice fashion.Type: GrantFiled: December 20, 1995Date of Patent: February 18, 1997Assignees: Hitachi, Ltd., Hitachi Device Engineering Co., Ltd.Inventors: Tsugio Takahashi, Goro Kitsukawa, Takesada Akiba, Yasushi Kawase, Masayuki Nakamura
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Patent number: 5448526Abstract: An intermediate voltage generating circuit for generating a voltage lying between an external power supply voltage and a ground voltage, and two voltage limiter circuits for generating internal power supply voltages and stabilized with this intermediate voltage as a reference are provided in a semiconductor integrated circuit. Even if the external power supply voltage or the ground voltage fluctuates, no disagreement is produced between a logical threshold of a circuit operating on the external power supply voltage and a logical threshold of a circuit operating on the internal power supply voltage.Type: GrantFiled: July 29, 1994Date of Patent: September 5, 1995Assignees: Hitachi, Ltd., Hitachi Device Engineering Co., Ltd.Inventors: Masashi Horiguchi, Kiyoo Itoh, Yoshiki Kawajiri, Goro Kitsukawa, Takayuki Kawahara, Takesada Akiba
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Patent number: 5347492Abstract: An intermediate voltage generating circuit for generating a voltage lying between an external power supply voltage and a ground voltage, and two voltage limiter circuits for generating internal power supply voltages and stabilized with this intermediate voltage as a reference are provided in a semiconductor integrated circuit. Even if the external power supply voltage or the ground voltage fluctuates, no disagreement is produced between a logical threshold of a circuit operating on the external power supply voltage and a logical threshold of a circuit operating on the internal power supply voltage.Type: GrantFiled: November 16, 1993Date of Patent: September 13, 1994Assignees: Hitachi, Ltd., Hitachi Device Engineering Co., Ltd.Inventors: Masashi Horiguchi, Kiyoo Itoh, Yoshiki Kawajiri, Goro Kitsukawa, Takayuki Kawahara, Takesada Akiba
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Patent number: 5337271Abstract: A semiconductor storage device is provided which minimizes current consumption by using a circuit which is fed by charges stored in a parasitic capacitance of another circuit. To this end, short-circuiting switches SP and SN are provided respectively between first common source lines PP1 and PN1 and second common source lines PP2 and PN2 of the semiconductor device. Electric charges on the first common source lines which have been amplified to its normal amplitude change the voltage level of the second common source lines. A data line connected to the second common source line is amplified to half of the normal amplitude. Thereafter, the signal on the data line is amplified by a sense amplifier. As a result, the charge and discharge currents on the data line are substantially halved compared to the conventional device.Type: GrantFiled: November 12, 1992Date of Patent: August 9, 1994Assignees: Hitachi, Ltd., Hitachi Device Engineering Co., Ltd.Inventors: Takayuki Kawahara, Yoshiki Kawajiri, Takesada Akiba, Mssashi Horiguchi, Goro Kitsukawa, Masakazu Aoki
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Patent number: 5300839Abstract: A sense amplifier circuit is provided for sensing a very small signal includes two MOS transistors responsive to a differential voltage between first and second input signal lines to conduct a differential operation and switches respectively connected between drain regions and gate regions respectively of the two MOS transistors. Before the circuit senses and amplifies the signal, the switches are turned on to generate threshold voltages between the gate regions and the source regions respectively of the two transistors. Consequently, according to the variation in the threshold voltage between the respective transistors, a self-adjustment is achieved on bias voltages of the transistors before the signal amplification. The sense amplifier circuit resultantly develops its operation independent of the variation in the threshold voltage. One use for this sense amplifier circuit is to serve as a sense amplifier for a DRAM.Type: GrantFiled: April 9, 1992Date of Patent: April 5, 1994Assignees: Hitachi, Ltd., Hitachi Device Engineering Co., Ltd.Inventors: Takayuki Kawahara, Takesada Akiba, Goro Kitsukawa, Yoshiki Kawajiri, Kiyoo Itoh, Takeshi Sakata
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Patent number: 5289425Abstract: An intermediate voltage generating circuit for generating a voltage lying between an external power supply voltage and a ground voltage, and two voltage limiter circuits for generating internal power supply voltages and stabilized with this intermediate voltage as a reference are provided in a semiconductor integrated circuit. Even if the external power supply voltage or the ground voltage fluctuates, no disagreement is produced between a logical threshold of a circuit operating on the external power supply voltage and a logical threshold of a circuit operating on the internal power supply voltage.Type: GrantFiled: April 17, 1992Date of Patent: February 22, 1994Assignee: Hitachi, Ltd.Inventors: Masashi Horiguchi, Kiyoo Itoh, Yoshiki Kawajiri, Goro Kitsukawa, Takayuki Kawahara, Takesada Akiba
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Patent number: 5274601Abstract: A device parameter of a switching transistor is set in such a way that a leakage current of the switching transistor making up a power source switch which is turned off in a stand-by state is smaller than the sum total of subthreshold currents of P-channel or N-channel MOS transistors in an off state of a plurality of CMOS circuits. Therefore, the currents which flow through the plurality of CMOS circuits in the stand-by state are not determined by the subthreshold current but are determined by a small leakage current of the switching transistor. As a result, even when the CMOS circuit is shrunken and the subthreshold current increases, it is possible to reduce the current consumption in the stand-by state.Type: GrantFiled: November 6, 1992Date of Patent: December 28, 1993Assignees: Hitachi, Ltd., Hitachi Device Engineering Co., Ltd.Inventors: Takayuki Kawahara, Yoshiki Kawajiri, Takesada Akiba, Masashi Horiguchi, Takao Watanabe, Goro Kitsukawa, Yasushi Kawase, Toshikazu Tachibana, Masakazu Aoki
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Patent number: 4873672Abstract: This invention relates to a semiconductor memory having a high speed operation and a high integration density. When a high integration semiconductor memory is applied to a large scale computer system, storage data must be erased at a high speed for data security. The present invention erases the storage data by a method which is different from the write method of conventional prior art. In the invention, the erasing operation is made by continuously selecting word lines while sense amplifiers are kept in this on-state. The present invention includes a control circuit for attaining such an operation, and can be used for a semiconductor memory implemented in a computer system accessed by a plurality of users.Type: GrantFiled: May 20, 1987Date of Patent: October 10, 1989Assignees: Hitachi, Ltd., Hitachi Device Engineering Co., Ltd.Inventors: Jun Etoh, Katsuhiro Shimohigashi, Kazuyuki Miyazawa, Katsutaka Kimura, Takesada Akiba