Patents by Inventor Yuji Kakinuma

Yuji Kakinuma 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: 20100301919
    Abstract: A mixer includes a magnetoresistive effect element, a magnetic field applying unit, and an impedance circuit. The magnetoresistive effect element includes a fixed magnetic layer, a free magnetic layer, and a nonmagnetic spacer layer disposed between the fixed magnetic layer and the free magnetic layer, is operable when a first high-frequency signal and a second high-frequency signal as a local signal are inputted, to multiply the first high-frequency signal and the second high-frequency signal according to a magnetoresistive effect to generate a multiplication signal. The magnetic field applying unit applies a magnetic field to the free magnetic layer. The impedance circuit has a higher impedance for the multiplication signal than an impedance for the first high-frequency signal and the second high-frequency signal and is disposed between an input transfer line, which transfers the first high-frequency signal and the second high-frequency signal, and the magnetoresistive effect element.
    Type: Application
    Filed: May 26, 2010
    Publication date: December 2, 2010
    Applicant: TDK CORPORATION
    Inventors: Yuji KAKINUMA, Ryoichi KONDO
  • Patent number: 7825658
    Abstract: A magnetic device includes: a magnetoresistive effect element having a magnetization fixed layer, a magnetization free layer, and a nonmagnetic layer sandwiched between the magnetization fixed layer and the magnetization free layer; an input terminal for feeding an AC signal to the magnetoresistive effect element in its stacking direction; and an output terminal for extracting an output voltage from the magnetoresistive effect element, wherein the nomagnetic layer includes an insulating layer portion comprising an insulating material, and a current-constricting layer portion comprising a conductive material which passes through the insulating layer portion in its film thickness direction.
    Type: Grant
    Filed: November 14, 2008
    Date of Patent: November 2, 2010
    Assignee: TDK Corporation
    Inventors: Keiji Koga, Yuji Kakinuma, Daisuke Miyauchi
  • Patent number: 7808813
    Abstract: There is provided a magnetic memory device capable of reading information even with a lower power supply voltage. The magnetic memory device is equipped with a plurality of storage cells laid out in two dimensions in (i+1) rows and (j+1) columns (where i, j are integers of one or higher). Two magnetoresistive effect revealing bodies 2a, 2b are disposed in each of the storage cells 1, and each storage cell includes: a first stage circuit 41 that supplies currents Ib1, Ib2 for detecting resistances of magnetoresistive effect revealing bodies 2a, 2b; an X-direction address decoder circuit 32 that supplies currents Iw1, Iw2 to the magnetoresistive effect revealing bodies 2a, 2b; and a current control circuit (constant current circuit 25n) that carries out control so that the total of the current Ib1 and the current Iw1 and the total of the current Iw2 and the current Ib2 are respectively constant.
    Type: Grant
    Filed: December 7, 2005
    Date of Patent: October 5, 2010
    Assignee: TDK Corporation
    Inventors: Joichiro Ezaki, Yuji Kakinuma
  • Patent number: 7808229
    Abstract: A magnetic device and a frequency analyzer are provided as those industrially utilizing a resonance phenomenon of a direction of magnetization of a magnetoresistive element. Since polarities of an alternating current i vary with time, the direction of magnetization oscillates as affected by the magnitude and frequency of the alternating current. When the frequency fF of the direction of magnetization of a free layer in the magnetoresistive element coincides with the frequency f of the alternating current flowing in the magnetoresistive element, the oscillation of the direction of magnetization resonates to increase a voltage between output terminals. A magnetic yoke applies such a magnetic field as to cause resonance, to the free layer. A direct current is used as an electric current outputted from a current control circuit and, while this direct current is swept, voltages at respective specific resonance frequencies are detected by a monitor circuit.
    Type: Grant
    Filed: December 10, 2007
    Date of Patent: October 5, 2010
    Assignee: TDK Corporation
    Inventors: Keiji Koga, Yuji Kakinuma
  • Publication number: 20090290405
    Abstract: There is provided a magnetic memory device capable of reading information even with a lower power supply voltage. The magnetic memory device is equipped with a plurality of storage cells laid out in two dimensions in (i+1) rows and (j+1) columns (where i, j are integers of one or higher). Two magnetoresistive effect revealing bodies 2a, 2b are disposed in each of the storage cells 1, and each storage cell includes: a first stage circuit 41 that supplies currents Ib1, Ib2 for detecting resistances of magnetoresistive effect revealing bodies 2a, 2b; an X-direction address decoder circuit 32 that supplies currents Iw1, Iw2 to the magnetoresistive effect revealing bodies 2a, 2b; and a current control circuit (constant current circuit 25n) that carries out control so that the total of the current Ib1 and the current Iw1 and the total of the current Iw2 and the current Ib2 are respectively constant.
    Type: Application
    Filed: December 7, 2005
    Publication date: November 26, 2009
    Applicant: TDK CORPORATION
    Inventors: Joichiro Ezaki, Yuji Kakinuma
  • Publication number: 20090243698
    Abstract: A mixer includes: a magnetoresistive effect element including a fixed magnetic layer, a free magnetic layer, and a nonmagnetic spacer layer disposed between the fixed magnetic layer and the free magnetic layer; and a magnetic field applying unit that applies a magnetic field to the free magnetic layer. The mixer is operable, when a first high-frequency signal and a second high-frequency signal as a local signal are inputted, to multiply the first high-frequency signal and the second high-frequency signal using the magnetoresistive effect element and to generate a multiplication signal. A frequency converting apparatus includes the mixer and a filter operable, when a higher frequency and a lower frequency out of frequencies of the first high-frequency signal and the second high-frequency signal are expressed as f1 and f2 respectively, to pass one out of a frequency (f1+f2) and a frequency (f1-f2) out of the multiplication signal.
    Type: Application
    Filed: February 24, 2009
    Publication date: October 1, 2009
    Applicant: TDK CORPORATION
    Inventors: Yuji KAKINUMA, Keiji KOGA
  • Publication number: 20090140733
    Abstract: A magnetic device includes: a magnetoresistive effect element having a magnetization fixed layer, a magnetization free layer, and a nonmagnetic layer sandwiched between the magnetization fixed layer and the magnetization free layer; an input terminal for feeding an AC signal to the magnetoresistive effect element in its stacking direction; and an output terminal for extracting an output voltage from the magnetoresistive effect element, wherein the nomagnetic layer includes an insulating layer portion comprising an insulating material, and a current-constricting layer portion comprising a conductive material which passes through the insulating layer portion in its film thickness direction.
    Type: Application
    Filed: November 14, 2008
    Publication date: June 4, 2009
    Applicant: TDK CORPORATION
    Inventors: Keiji KOGA, Yuji KAKINUMA, Daisuke MIYAUCHI
  • Patent number: 7522450
    Abstract: A magnetic storage cell being capable of stable writing and having little adverse influence on an adjacent magnetic storage cell, and a magnetic memory device using the magnetic storage cell, and its manufacturing method are provided. In the invention, a plurality of TMR devices (1a) (1b) each including a TMR film (S20) including a connecting portion (14) of which the magnetization direction is changed by an external magnetic field and a second magnetic layer (8) and allowing a current to flow therethrough in a direction perpendicular to a laminate surface, and a toroidal magnetic layer (4) disposed on a surface of the TMR film (S20) so that a direction along the laminate surface is an axial direction and a write bit line (5) and a write word line (6) penetrate through the toroidal magnetic layer (4) are included, and the TMR devices (1a), (1b) share a part of the toroidal magnetic layer (4) between them.
    Type: Grant
    Filed: January 21, 2004
    Date of Patent: April 21, 2009
    Assignee: TDK Corporation
    Inventors: Joichiro Ezaki, Keiji Koga, Yuji Kakinuma, Susumu Haratani
  • Publication number: 20080180085
    Abstract: A magnetic device and a frequency analyzer are provided as those industrially utilizing a resonance phenomenon of a direction of magnetization of a magnetoresistive element. Since polarities of an alternating current i vary with time, the direction of magnetization oscillates as affected by the magnitude and frequency of the alternating current. When the frequency fF of the direction of magnetization of a free layer in the magnetoresistive element coincides with the frequency f of the alternating current flowing in the magnetoresistive element, the oscillation of the direction of magnetization resonates to increase a voltage between output terminals. A magnetic yoke applies such a magnetic field as to cause resonance, to the free layer. A direct current is used as an electric current outputted from a current control circuit and, while this direct current is swept, voltages at respective specific resonance frequencies are detected by a monitor circuit.
    Type: Application
    Filed: December 10, 2007
    Publication date: July 31, 2008
    Applicant: TDK CORPORATION
    Inventors: Keiji Koga, Yuji Kakinuma
  • Patent number: 7352615
    Abstract: A magnetic memory device which can be formed with a further reduced size. The magnetic memory device includes: a plurality of memory cells each including at least one magnetoresistive effect revealing body and arranged along a pair of lines; a plurality of auxiliary write lines arranged so that each memory cell is provided with one auxiliary write line, each auxiliary write line being connected to the pair of lines, for introducing write currents flowing through the pair of lines to the vicinity of the magnetoresistive effect revealing body; and transistors arranged so that one transistor is inserted in each auxiliary write line, for allowing the write current to flow bidirectionally through the auxiliary write line in an operating state of the transistors.
    Type: Grant
    Filed: April 12, 2006
    Date of Patent: April 1, 2008
    Assignee: TDX Corporation
    Inventors: Joichiro Ezaki, Yuji Kakinuma
  • Patent number: 7349244
    Abstract: A magnetic memory device includes a plurality of storage cells disposed in two dimensions, read lines that supply a read current for reading information from a first power supply to the respective storage cells, and a second power supply that is connected to at least some of the read lines and applies an intermediate voltage, which is lower than the voltage supplied by the first power supply, to the connected read lines.
    Type: Grant
    Filed: July 24, 2006
    Date of Patent: March 25, 2008
    Assignee: TDK Corporation
    Inventors: Joichiro Ezaki, Yuji Kakinuma
  • Patent number: 7342822
    Abstract: The number of write circuit components, variations in a write current flowing through each write line, and the power consumption for write operation can be reduced. A first constant current circuit and a second constant current circuit (a transistor (Q8) and a resistor (R4), and a transistor (Q7) and a resistor (R3)) are shared among a plurality of current direction control portions (54n?1, 54n, 54n+1, . . . ). The constant current circuits are connected to each current direction control portion (54) through a first circuit selector switch (SW1 . . . , SW1n, SW1n+1, . . . ) and a second circuit selector switch (SW2 . . . , SW2n, SW2n+1, . . . ) disposed for each current direction control portion (54). Moreover, a decode signal voltage is applied to the constant current circuits from a word decode line (16X) (bit decode line (16Y)) through the circuit selector switches (SW1) and (SW2).
    Type: Grant
    Filed: January 15, 2004
    Date of Patent: March 11, 2008
    Assignee: TDK Corporation
    Inventors: Joichiro Ezaki, Yuji Kakinuma, Keiji Koga, Shigekazu Sumita
  • Patent number: 7295460
    Abstract: The present invention provides a magnetic memory device capable of reducing a loss of a magnetic field generated by currents flowing in a write line and performing writing stably, and a magnetic memory cell mounted on the magnetic memory device. Further, the invention provides a method for easily manufacturing such a magnetic memory device. A magnetic memory cell includes: stacked bodies each including a magneto-sensitive layer whose magnetization direction changes according to an external magnetic field, and constructed so that current flows in a direction perpendicular to a stack layer surface; and a toroidal magnetic layer disposed between the first and second stacked bodies so that the direction along the stack layer surface is set as an axial direction, and constructed so as to be penetrated by a plurality of conductors along the axial direction.
    Type: Grant
    Filed: March 26, 2004
    Date of Patent: November 13, 2007
    Assignee: TDK Corporation
    Inventors: Joichiro Ezaki, Keiji Koga, Yuji Kakinuma
  • Patent number: 7277320
    Abstract: A magnetic memory device and a sense amplifier circuit capable of obtaining a read signal output with a high S/N ratio and reducing power consumption and a circuit space, and a method of reading from a magnetic memory device are provided. In a sense amplifier, transistors (41A), (41B) which are differential amplifiers are commonly connected to one constant current circuit (50) through switches (46) ( . . . , 46n, 46n+1, . . . ). Corresponding bit decode lines (20) ( . . . , 20n, 20n+1, . . . ) and a read selection signal line (90) are connected to the switches (46) ( . . . , 46n, 46n+1, . . . ). A read/write signal is transferred from the read selection signal line (90), and the switches (46) operate according to a bit decode value and the read/write signal.
    Type: Grant
    Filed: March 23, 2004
    Date of Patent: October 2, 2007
    Assignee: TDK Corporation
    Inventors: Joichiro Ezaki, Yuji Kakinuma, Keiji Koga, Shigekazu Sumita
  • Patent number: 7230843
    Abstract: The present invention provides a magnetic memory device based on a novel driving method realizing reliable writing and a method of writing the magnetic memory device. Four parallel portions are formed in a pair of loop-shaped write lines (6Xn) and (6Yn). Magnetoresistive devices (12A) and (12B) disposed in the parallel portion in an upper stage construct a memory cell (12Ev), and magnetoresistive devices (12A) and (12B) disposed in the parallel portion in a lower stage construct a memory cell (12Od). When current in the direction from the drive point A to the drive point B is passed from the current drives (123n) and (133n), the directions of the currents in the write lines (6Xn) and (6Yn) are aligned in the parallel portion of the memory cell (12Ev) but are opposite to each other in the parallel portion in the memory cell (12Od).
    Type: Grant
    Filed: March 26, 2004
    Date of Patent: June 12, 2007
    Assignee: TDK Corporation
    Inventors: Joichiro Ezaki, Yuji Kakinuma, Keiji Koga, Shigekazu Sumita
  • Patent number: 7227771
    Abstract: A magnetoresistive effect element includes a TMR element disposed at an intersection where a bit line and a write word line intersect, in a manner sandwiched between the bit line and the write word line, and is configured such that it includes a sensitive magnetic layer whose magnetization direction is changed by a synthetic magnetic field of magnetic fields generated around the bit line and the write word line, and at the same time such that electric current flows in a direction perpendicular to the laminating surfaces thereof, and a magnetic material individually covering the bit line and the write word line at the intersection, thereby forming an annular magnetic layer associated with the bit line and an annular magnetic layer associated with the write word line.
    Type: Grant
    Filed: March 12, 2004
    Date of Patent: June 5, 2007
    Assignee: TDK Corporation
    Inventors: Joichiro Ezaki, Keiji Koga, Yuji Kakinuma
  • Patent number: 7209380
    Abstract: The present invention provides a magnetic memory device capable of performing reading operation with lower power consumption and at high read precision and a method of reading the magnetic memory device. Sense bit lines (21A, 21B) are provided in a bit line direction for each pair of magnetoresistive devices (12A, 12B) constructing a storage cell (12) and a read current is supplied. The read currents passed through the pair of magnetoresistive devices (12A, 12B) flow to the ground via a sense word line (31). Further, by providing a constant current circuit (108B) commonly for plural sense word lines (31), the sum of a pair of read currents passing through the pair of magnetoresistive devices (12A, 12B) in one storage cell constant, and information is read from the storage cell (12) on the basis of the difference between the pair of read currents. By sharing the constant current circuit (108B), variations in the sum of the pair of read currents can be reduced, and power consumption can be also reduced.
    Type: Grant
    Filed: March 12, 2004
    Date of Patent: April 24, 2007
    Assignee: TDK Corporation
    Inventors: Joichiro Ezaki, Yuji Kakinuma, Keiji Koga, Shigekazu Sumita
  • Publication number: 20070019462
    Abstract: The present invention provides a magnetic memory device capable of reducing a loss of a magnetic field generated by currents flowing in a write line and performing writing stably, and a magnetic memory cell mounted on the magnetic memory device. Further, the invention provides a method for easily manufacturing such a magnetic memory device. A magnetic memory cell includes: stacked bodies each including a magneto-sensitive layer whose magnetization direction changes according to an external magnetic field, and constructed so that current flows in a direction perpendicular to a stack layer surface; and a toroidal magnetic layer disposed between the first and second stacked bodies so that the direction along the stack layer surface is set as an axial direction, and constructed so as to be penetrated by a plurality of conductors along the axial direction.
    Type: Application
    Filed: March 26, 2004
    Publication date: January 25, 2007
    Applicant: TDK CORPORATION
    Inventors: Joichiro Ezaki, Keiji Koga, Yuji Kakinuma
  • Publication number: 20070019464
    Abstract: A magnetic memory device includes a plurality of storage cells disposed in two dimensions, read lines that supply a read current for reading information from a first power supply to the respective storage cells, and a second power supply that is connected to at least some of the read lines and applies an intermediate voltage, which is lower than the voltage supplied by the first power supply, to the connected read lines.
    Type: Application
    Filed: July 24, 2006
    Publication date: January 25, 2007
    Applicant: TDK CORPORATION
    Inventors: Joichiro EZAKI, Yuji KAKINUMA
  • Publication number: 20060256461
    Abstract: The number of write circuit components, variations in a write current flowing through each write line, and the power consumption for write operation can be reduced. A first constant current circuit and a second constant current circuit (a transistor (Q8) and a resistor (R4), and a transistor (Q7) and a resistor (R3)) are shared among a plurality of current direction control portions (54n?1, 54n, 54n+1, . . . ). The constant current circuits are connected to each current direction control portion (54) through a first circuit selector switch (SW1 . . . , SW1n, SW1n+1, . . . ) and a second circuit selector switch (SW2 . . . , SW2n, SW2n+1, . . . ) disposed for each current direction control portion (54). Moreover, a decode signal voltage is applied to the constant current circuits from a word decode line (16X) (bit decode line (16Y)) through the circuit selector switches (SW1) and (SW2).
    Type: Application
    Filed: January 15, 2004
    Publication date: November 16, 2006
    Inventors: Joichiro Ezaki, Yuji Kakinuma, Keiji Koga, Shigekazu Sumita