Patents by Inventor Hirokazu Yamazaki
Hirokazu Yamazaki 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: 8542041Abstract: A first transistor has one end and a gate coupled to a first power supply line and other end coupled to a first node. A second transistor has a gate coupled to a second node, one end coupled to the first node, and other end coupled to a third node. A third transistor has one end coupled to a second power supply line, a gate coupled to a fourth node, and other end coupled to the third node. A first bias voltage generation circuit supplies a first bias voltage to the second node. A second bias voltage generation circuit supplies a second bias voltage to the fourth node. Accordingly, the power supply voltage at which the third node is changed from a certain level to another level is set high, and an internal node in a semiconductor device is securely initialized when the power supply voltage is decreased.Type: GrantFiled: April 6, 2010Date of Patent: September 24, 2013Assignee: Fujitsu Semiconductor LimitedInventors: Mitsuhiro Ogai, Hirokazu Yamazaki, Keizo Morita, Kazuaki Yamane, Yasuhiro Fujii, Kazuaki Takai, Shoichiro Kawashima
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Publication number: 20100253419Abstract: A first transistor has one end and a gate coupled to a first power supply line and other end coupled to a first node. A second transistor has a gate coupled to a second node, one end coupled to the first node, and other end coupled to a third node. A third transistor has one end coupled to a second power supply line, a gate coupled to a fourth node, and other end coupled to the third node. A first bias voltage generation circuit supplies a first bias voltage to the second node. A second bias voltage generation circuit supplies a second bias voltage to the fourth node. Accordingly, the power supply voltage at which the third node is changed from a certain level to another level is set high, and an internal node in a semiconductor device is securely initialized when the power supply voltage is decreased.Type: ApplicationFiled: April 6, 2010Publication date: October 7, 2010Applicant: FUJITSU MICROELECTRONICS LIMITEDInventors: Mitsuhiro OGAI, Hirokazu Yamazaki, Keizo Morita, Kazuaki Yamane, Yasuhiro Fujii, Kazuaki Takai, Shoichiro Kawashima
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Patent number: 7545186Abstract: A reset circuit includes a power supply detection circuit, a power-down detection circuit, and an output circuit. The power supply detection circuit outputs a first signal when a first voltage according to a power supply voltage is higher than a first threshold and outputting a second signal when the first voltage is lower than the first threshold during power-on and power-down. The power-down detection circuit outputs a third signal when a second voltage according to the power supply voltage becomes lower than a second threshold after the second signal is outputted during power-down. The output circuit outputs a power-on reset signal which changes from low to high when the first signal is outputted during power-on and outputs a power-down reset signal which changes from low to high when the third signal is outputted during power-down.Type: GrantFiled: November 29, 2004Date of Patent: June 9, 2009Assignee: Fujitsu Microelectroncis LimitedInventors: Hideaki Suzuki, Hirokazu Yamazaki
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Publication number: 20050275437Abstract: A reset circuit includes a power supply detection circuit, a power-down detection circuit, and an output circuit. The power supply detection circuit outputs a first signal when a first voltage according to a power supply voltage is higher than a first threshold and outputting a second signal when the first voltage is lower than the first threshold during power-on and power-down. The power-down detection circuit outputs a third signal when a second voltage according to the power supply voltage becomes lower than a second threshold after the second signal is outputted during power-down. The output circuit outputs a power-on reset signal which changes from low to high when the first signal is outputted during power-on and outputs a power-down reset signal which changes from low to high when the third signal is outputted during power-down.Type: ApplicationFiled: November 29, 2004Publication date: December 15, 2005Inventors: Hideaki Suzuki, Hirokazu Yamazaki
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Patent number: 6777736Abstract: The semiconductor device having the capacitor comprises a plurality of switching elements formed on a semiconductor substrate 1 at a distance, a plurality of capacitors formed in areas between a plurality of switching elements formed in the first direction respectively and each having a lower electrode, a dielectric film and an upper electrode, first wirings for connecting the upper electrodes of the capacitors and the switching elements in the first direction on a one-by-one base, and second wirings formed over a part of the first wirings, the switching elements, and the capacitors to extend in the second direction that intersects with the first direction. Accordingly, the higher speed operation than the prior art can be achieved.Type: GrantFiled: October 9, 2001Date of Patent: August 17, 2004Assignee: Fujitsu LimitedInventors: Kaoru Saigoh, Hisashi Miyazawa, Hirokazu Yamazaki, Hideaki Suzuki
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Patent number: 6496428Abstract: A redundancy information region having memory cells for retaining relief information indicating the locations of defective memory cells is arranged closer to at least one of a word driver or a plate driver than a memory cell region and a redundancy memory cell region. Since the memory cells of the redundancy information region start operation earlier, a relief/no-relief judgment can be made earlier, allowing reduction in access time. Besides, in memory cell operations, the defective memory cells are deselected in accordance with address information held in a redundancy address region. Redundancy memory cells for relieving the defective memory cells are selected in accordance with the relief information held in a redundancy flag region. Since the redundancy memory cells are selected without using the address information, it is possible to reduce the time that elapses before the redundancy memory cells are selected after the selection of word lines.Type: GrantFiled: September 28, 2001Date of Patent: December 17, 2002Assignee: Fujitsu LimitedInventors: Chikai Ohno, Hirokazu Yamazaki, Hideaki Suzuki
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Publication number: 20020130345Abstract: The semiconductor device having the capacitor comprises a plurality of switching elements formed on a semiconductor substrate 1 at a distance, a plurality of capacitors formed in areas between a plurality of switching elements formed in the first direction respectively and each having a lower electrode, a dielectric film and an upper electrode, first wirings for connecting the upper electrodes of the capacitors and the switching elements in the first direction on a one-by-one base, and second wirings formed over a part of the first wirings, the switching elements, and the capacitors to extend in the second direction that intersects with the first direction. Accordingly, the higher speed operation than the prior art can be achieved.Type: ApplicationFiled: October 9, 2001Publication date: September 19, 2002Applicant: Fujitsu LimitedInventors: Kaoru Saigoh, Hisashi Miyazawa, Hirokazu Yamazaki, Hideaki Suzuki
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Publication number: 20020097618Abstract: A redundancy information region having memory cells for retaining relief information indicating the locations of defective memory cells is arranged closer to at least one of a word driver or a plate driver than a memory cell region and a redundancy memory cell region. Since the memory cells of the redundancy information region start operation earlier, a relief/no-relief judgment can be made earlier, allowing reduction in access time. Besides, in memory cell operations, the defective memory cells are deselected in accordance with address information held in a redundancy address region. Redundancy memory cells for relieving the defective memory cells are selected in accordance with the relief information held in a redundancy flag region. Since the redundancy memory cells are selected without using the address information, it is possible to reduce the time that elapses before the redundancy memory cells are selected after the selection of word lines.Type: ApplicationFiled: September 28, 2001Publication date: July 25, 2002Applicant: FUJITSU LIMITEDInventors: Chikai Ohno, Hirokazu Yamazaki, Hideaki Suzuki
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Patent number: 6229728Abstract: A ferroelectric memory includes memory cells, a pair of bit lines to which the memory cells are connected, and a control circuit which changes a reference cell applied to one of the pair of bit lines while data read from one of the memory cells is output to the other one of the pair of bit lines.Type: GrantFiled: April 22, 1999Date of Patent: May 8, 2001Assignee: Fujitu LimitedInventors: Chikai Ono, Hirokazu Yamazaki
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Patent number: 6072724Abstract: Disclosed is an art making it possible that, in a reference cell circuit for outputting a plurality of different reference level signals, even if the number of transistors serving as reference cells and each having a floating gate increases, the time required for setting channel currents of the transistors will not increase. The floating gates of a plurality of transistors for generating different reference signal levels are connected in common so that the channel currents of all the transistors can be set simultaneously. The transistors have the channel lengths thereof, channel widths thereof, or both of them made different. The channel currents of the transistors are therefore mutually different. An error in all reference levels dependent on a manufacturing process is compensated for by adjusting an amount of charge to be injected into the floating gates.Type: GrantFiled: July 29, 1997Date of Patent: June 6, 2000Assignee: Fujitsu LimitedInventor: Hirokazu Yamazaki
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Patent number: 5592427Abstract: An object of the present invention is to provide a semiconductor device that permits easy and efficient testing. A nonvolatile semiconductor memory comprises word lines WLi and bit lines BLi, a memory cell matrix 17 consisting of nonvolatile memory cells Cij, a sense amplifier 15, a write/erase timing circuit 9 for performing timing control necessary for write and erase operations, and a status register 2 for storing the operating state of the memory at the completion of the operation of the circuit 9, wherein there are provided, outside the address of the memory cell matrix 17, two kinds of dummy cells, D1, D2, D3, . . . , whose values are fixed to different values that induce different outputs from the sense amplifier 15. A pass condition or a fail condition is generated by accessing the dummy cells.Type: GrantFiled: June 6, 1995Date of Patent: January 7, 1997Assignee: Fujitsu LimitedInventors: Sinsuke Kumakura, Hirokazu Yamazaki, Hisayoshi Watanabe, Yasushi Kasa
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Patent number: 5566386Abstract: An object of the present invention is to provided a semiconductor device that permits easy and efficient testing. A semiconductor device which is characterized in that the power supply for an output circuit is selectable between a normal power supply and an independent power supply provided independently of the normal supply.Type: GrantFiled: June 6, 1995Date of Patent: October 15, 1996Assignee: Fujitsu LimitedInventors: Sinsuke Kumakura, Hirokazu Yamazaki, Hisayoshi Watanabe, Yasushi Kasa
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Patent number: 5469381Abstract: A semiconductor memory having a non-volatile semiconductor memory cell, wherein the depletion of electrons from the semiconductor memory cell takes place in conjunction with the depletion of electrons from a load transistor so that a voltage difference between each threshold voltage can be maintained at the same level, and a writing operation is performed in a configuration where the load transistor of the non-volatile semiconductor memory cell is equipped with, like the non-volatile semiconductor memory cell, a floating gate, so that an initially stored memory content of the semiconductor memory cell can be read out.Type: GrantFiled: November 16, 1992Date of Patent: November 21, 1995Assignee: Fujitsu LimitedInventor: Hirokazu Yamazaki
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Patent number: 5469394Abstract: An object of the present invention is to provide a semiconductor device that permits easy and efficient testing. A nonvolatile semiconductor memory comprises word lines WLi and bit lines BLi, a memory cell matrix 17 consisting of nonvolatile memory cells Cij, a sense amplifier 15, a write/erase timing circuit 9 for performing timing control necessary for write and erase operations, and a status register 2 for storing the operating state of the memory at the completion of the operation of the circuit 9, wherein there are provided, outside the address of the memory cell matrix 17, two kinds of dummy cells, D1, D2, D3, . . . , whose values are fixed to different values that induce different outputs from the sense amplifier 15. A pass condition or a fail condition is generated by accessing the dummy cells.Type: GrantFiled: December 29, 1994Date of Patent: November 21, 1995Assignee: Fujitsu LimitedInventors: Sinsuke Kumakura, Hirokazu Yamazaki, Hisayoshi Watanabe, Yasushi Kasa
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Patent number: 5402380Abstract: An object of the present invention is to provide a semiconductor device that permits easy and efficient testing. A nonvolatile semiconductor memory including word lines WLi and bit lines BLi, a memory cell matrix 17 including nonvolatile memory cells Cij, a sense amplifier 15, a write/erase timing circuit 9 for performing timing control necessary for write and erase operations, and a status register 2 for storing the operating state of the memory at the completion of the operation of the circuit 9, wherein there are provided, outside the address of the memory cell matrix 17, two kinds of dummy cells, D1, D2, D3, . . . , whose values are fixed to different values that induce different outputs from the sense amplifier 15. A pass condition or a fail condition is generated by accessing the dummy cells.Type: GrantFiled: February 7, 1994Date of Patent: March 28, 1995Assignee: Fujitsu LimitedInventors: Sinsuke Kumakura, Hirokazu Yamazaki, Hisayoshi Watanabe, Yasushi Kasa
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Patent number: 5149990Abstract: A semiconductor device for absorbing a noise comprises a first and second buffer. The first and second buffers receive an external signal having a rising edge and a falling edge, and performs waveform shaping thereof to produce an output signal. The first buffer, which issues an output signal for controlling the internal circuits of a chip of the semiconductor device so as to make the chip's internal circuits active/stand-by, is not sensitive to the rising edge of the external signal, but is sensitive to the falling edge of the same external signal. The second buffer, which issues an output signal for controlling an output circuit of a chip of the semiconductor device so as to make the output circuit active/stand-by, is sensitive to both the rising and the falling edges of the external signal.Type: GrantFiled: January 18, 1991Date of Patent: September 22, 1992Assignee: Fujitsu LimitedInventors: Hirokazu Yamazaki, Masanobu Yoshida