Patents by Inventor Ryuji Takishita

Ryuji Takishita 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: 20110175639
    Abstract: To provide a semiconductor device including an interface chip and a core chip and a measurement-target signal line and a reference signal line each including a through silicon via provided in the core chip and electrically connecting the interface chip and the core chip. The interface chip outputs a test clock generated by a first signal generation circuit to the core chip. The core chip includes a second signal generation circuit that generates a predetermined measurement signal from the test clock, and outputs the predetermined measurement signal to the measurement-target signal line and the reference signal line in a simultaneous manner. Further, the interface chip detects a phase difference of a plurality of predetermined measurement signals input via the measurement-target signal line and the reference signal line by an operational amplifier, and outputs a test result to a determination circuit.
    Type: Application
    Filed: January 14, 2011
    Publication date: July 21, 2011
    Applicant: Elpida Memory, Inc.
    Inventors: Hideyuki Yoko, Kentaro Hara, Ryuji Takishita
  • Publication number: 20110093735
    Abstract: Each of the core chips includes a data output circuit that outputs read data to the interface chip in response to a read command, and an output timing adjustment circuit that equalizes the periods of time required between the reception of the read command and the outputting of the read data from the data output circuit among the core chips. With this arrangement, a sufficient latch margin for read data to be input can be secured on the interface chip side. Furthermore, as the output timing is adjusted on each core chip side, there is no need to prepare the same number of latch timing control circuits as the number of core chips on the interface chip side.
    Type: Application
    Filed: October 7, 2010
    Publication date: April 21, 2011
    Applicant: Elpida Memory, Inc.
    Inventors: Hideyuki Yoko, Naohisa Nishioka, Chikara Kondo, Ryuji Takishita
  • Publication number: 20110057819
    Abstract: In a stacked semiconductor device in which a plurality of through silicon vias used for data transfer are shared among a plurality of semiconductor chips, a first semiconductor chip included in the semiconductor chips holds through silicon via switching information for specifying a through silicon via among the through silicon vias to be used for data transfer, and transfers the through silicon via switching information to a second semiconductor chip included in the semiconductor chips. According to the present invention, because the through silicon via switching information is transferred from the first semiconductor chip to the second semiconductor chip, a circuit for storing the through silicon via switching information in a nonvolatile manner is not required in the second semiconductor chip. With this arrangement, a chip area of the second semiconductor chip can be reduced.
    Type: Application
    Filed: October 8, 2010
    Publication date: March 10, 2011
    Applicant: Elpida Memory, Inc.
    Inventors: Akira Ide, Ryuji Takishita
  • Publication number: 20110050304
    Abstract: In a semiconductor device, there are provided first to third pairs of nMOS transistors between a GND and two sense nodes and first to third pairs of pMOS transistors between the two sense nodes and the power supply. A first internal clock signal and its inverted signal are supplied to gates of the first pair of nMOS transistors and the second pair of nMOS transistors, respectively. Complementary external clock signals are supplied to the gates of the third pairs of nMOS transistors and the third pairs of pMOS transistors. An inverted version of a second internal clock signal and the second internal clock signal are supplied to gates of the first and second pairs of pMOS transistors. The two sense nodes are connected to inputs of a differential amplifier. The output of the differential amplifier is latched by a latch circuit. Also provided an equalizing circuit precharging/equalizing the two sense nodes (FIG. 2).
    Type: Application
    Filed: August 30, 2010
    Publication date: March 3, 2011
    Applicant: Elpida Memory, Inc.
    Inventors: Koji Kuroki, Ryuji Takishita
  • Patent number: 7576579
    Abstract: A DLL circuit includes a first delay adjusting circuit that adjusts an amount of delay of a frequency-divided signal CK1, a second delay adjusting circuit that adjusts an amount of delay of a frequency-divided signal CK2, a synthesizing circuit that synthesizes outputs of these delay adjusting circuits to generate an internal clock signal, and supplies the internal clock signal to a real path, a clock driver that receives the output of the first delay adjusting circuit and supplies the output to a replica path, and a clock driver that receives the output of the second delay adjusting circuit. These clock drivers have substantially the same circuit configuration. Accordingly, even when the power supply voltage fluctuates, influences of the fluctuations on the respective frequency-divided signals are almost equal. Thus, deterioration of the function of the DLL circuit due to fluctuations of the power supply voltage can be prevented.
    Type: Grant
    Filed: August 23, 2007
    Date of Patent: August 18, 2009
    Assignee: Elpida Memory, Inc.
    Inventors: Hiroki Fujisawa, Ryuji Takishita
  • Patent number: 7477083
    Abstract: A delay amount variable circuit (8) adapted to change a delay amount according to a ZQ calibration result is inserted in a path of a DQ replica system. The delay amount of the path of the DQ replica system is variable and is adjusted so as to make constant a timing skew difference between a DQ buffer system and the DQ replica system. The ZQ calibration result changes depending on variations in temperature, voltage, and manufacture. Therefore, by obtaining the delay amount corresponding to these variations, there are obtained a DLL circuit with high accuracy that can make the skew difference constant, and a semiconductor device incorporating such a DLL circuit.
    Type: Grant
    Filed: October 24, 2006
    Date of Patent: January 13, 2009
    Assignee: Elpida Memory, Inc.
    Inventors: Hiroki Fujisawa, Ryuji Takishita
  • Publication number: 20080054959
    Abstract: A DLL circuit includes a first delay adjusting circuit that adjusts an amount of delay of a frequency-divided signal CK1, a second delay adjusting circuit that adjusts an amount of delay of a frequency-divided signal CK2, a synthesizing circuit that synthesizes outputs of these delay adjusting circuits to generate an internal clock signal, and supplies the internal clock signal to a real path, a clock driver that receives the output of the first delay adjusting circuit and supplies the output to a replica path, and a clock driver that receives the output of the second delay adjusting circuit. These clock drivers have substantially the same circuit configuration. Accordingly, even when the power supply voltage fluctuates, influences of the fluctuations on the respective frequency-divided signals are almost equal. Thus, deterioration of the function of the DLL circuit due to fluctuations of the power supply voltage can be prevented.
    Type: Application
    Filed: August 23, 2007
    Publication date: March 6, 2008
    Inventors: Hiroki Fujisawa, Ryuji Takishita
  • Publication number: 20070152680
    Abstract: Accurate duty detection is enabled by performing duty detection once every two cycles while delaying detection of one clock logic level by a half cycle, and presetting the potential of a common contact to an initial set value during the delay time. A DLL circuit employing a divide-by-two scheme is provided with separate duty detection circuits for even-numbered and odd-numbered cycles to detect duties of the respective cycles, respectively. The DLL circuit having this configuration and a semiconductor device having such DLL circuit are capable of accurate timing adjustment to the clock.
    Type: Application
    Filed: October 27, 2006
    Publication date: July 5, 2007
    Inventors: Hiroki FUJISAWA, Ryuji TAKISHITA
  • Publication number: 20070132493
    Abstract: A delay amount variable circuit (8) adapted to change a delay amount according to a ZQ calibration result is inserted in a path of a DQ replica system. The delay amount of the path of the DQ replica system is variable and is adjusted so as to make constant a timing skew difference between a DQ buffer system and the DQ replica system. The ZQ calibration result changes depending on variations in temperature, voltage, and manufacture. Therefore, by obtaining the delay amount corresponding to these variations, there are obtained a DLL circuit with high accuracy that can make the skew difference constant, and a semiconductor device incorporating such a DLL circuit.
    Type: Application
    Filed: October 24, 2006
    Publication date: June 14, 2007
    Inventors: Hiroki Fujisawa, Ryuji Takishita