Patents by Inventor Ryuta Nagai

Ryuta Nagai 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).

  • Patent number: 11876090
    Abstract: An electrostatic discharge protection circuit capable of clamping both positive and negative ESD events and passing signals is provided. Generally, the circuit includes a p-channel field-effect transistor (PFET) clamp coupled to a pin to be protected, the PFET clamp including a plurality of PFETs in a DN-well, an n-channel field-effect transistors (NFET) clamp coupled between ground and the pin through the PFET clamp, the NFET clamp including a plurality of NFETs coupled in series, and a bias network for biasing a voltage of the DN well to substantially equal a voltage on the pin when the voltage on the pin is greater than ground potential, and to ground potential when the pin voltage is less than ground potential. The plurality of are PFETs coupled in parallel between the pin and the NFET clamp, each of the PFETs is coupled to the pin though one of a plurality ballast resistors.
    Type: Grant
    Filed: November 17, 2022
    Date of Patent: January 16, 2024
    Assignee: Cypress Semiconductor Corporation
    Inventors: David Michael Rogers, Eric N. Mann, Eric Lee Swindlehurst, Toru Miyamae, Timothy John Williams, Ryuta Nagai, Sungkwon Lee, Ravindra M. Kapre, Mimi Xuefeng Zhao Qian, Yan Yi, Dung Si Ho, Boo Chin-Hua
  • Publication number: 20230343779
    Abstract: An electrostatic discharge protection circuit capable of clamping both positive and negative ESD events and passing signals is provided. Generally, the circuit includes a p-channel field-effect transistor (PFET) clamp coupled to a pin to be protected, the PFET clamp including a plurality of PFETs in a DN-well, an n-channel field-effect transistors (NFET) clamp coupled between ground and the pin through the PFET clamp, the NFET clamp including a plurality of NFETs coupled in series, and a bias network for biasing a voltage of the DN well to substantially equal a voltage on the pin when the voltage on the pin is greater than ground potential, and to ground potential when the pin voltage is less than ground potential. The plurality of are PFETs coupled in parallel between the pin and the NFET clamp, each of the PFETs is coupled to the pin though one of a plurality ballast resistors.
    Type: Application
    Filed: November 17, 2022
    Publication date: October 26, 2023
    Applicant: Cypress Semiconductor Corporation
    Inventors: David Michael Rogers, Eric N. Mann, Eric Lee Swindlehurst, Toru Miyamae, Timothy John Williams, Ryuta Nagai, Sungkwon Lee, Ravindra M. Kapre, Mimi Xuefeng Zhao Qian, Yan Yi, Dung Si Ho, Boo Chin-Hua
  • Patent number: 11521962
    Abstract: An electrostatic discharge protection circuit capable of clamping both positive and negative ESD events and passing signals is provided. Generally, the circuit includes a p-channel field-effect transistor (PFET) clamp coupled to a pin to be protected, the PFET clamp including a plurality of PFETs in a DN-well, an n-channel field-effect transistors (NFET) clamp coupled between ground and the pin through the PFET clamp, the NFET clamp including a plurality of NFETs coupled in series, and a bias network for biasing a voltage of the DN well to substantially equal a voltage on the pin when the voltage on the pin is greater than ground potential, and to ground potential when the pin voltage is less than ground potential. The plurality of are PFETs coupled in parallel between the pin and the NFET clamp, each of the PFETs is coupled to the pin though one of a plurality ballast resistors.
    Type: Grant
    Filed: September 14, 2021
    Date of Patent: December 6, 2022
    Assignee: Cypress Semiconductor Corporation
    Inventors: David Michael Rogers, Eric N. Mann, Eric Lee Swindlehurst, Toru Miyamae, Timothy John Williams, Ryuta Nagai, Sungkwon Lee, Ravindra M. Kapre, Mimi Xuefeng Zhao Qian, Yan Yi, Dung Si Ho, Boo Chin-Hua
  • Patent number: 8988052
    Abstract: A control circuit for controlling a power supply including a first switch and a second switch coupled in series between a first potential and a second potential. The control circuit includes a detection circuit that detects a magnitude relation of a voltage value at a node between the first and second switches and a reference value during a period in which the first switch and the second switch are inactivated. The detection circuit generates a control signal corresponding to the magnitude relation. A regulation circuit regulates a switching timing of the second switch in response to the control signal to decrease a difference between the voltage value at the node and the reference value.
    Type: Grant
    Filed: April 15, 2011
    Date of Patent: March 24, 2015
    Assignee: Spansion LLC
    Inventors: Kazuyoshi Futamura, Takashi Matsumoto, Ryuta Nagai
  • Patent number: 8698465
    Abstract: A control circuit for controlling a power supply including a first switch and a second switch coupled in series between a first potential and a second potential. The control circuit includes a detection circuit that detects a magnitude relation of a voltage value at a node between the first and second switches and a reference value during a period in which the first switch and the second switch are inactivated. The detection circuit generates a control signal corresponding to the magnitude relation. A regulation circuit regulates a switching timing of the second switch in response to the control signal to decrease a difference between the voltage value at the node and the reference value.
    Type: Grant
    Filed: April 15, 2011
    Date of Patent: April 15, 2014
    Assignee: Spansion LLC
    Inventors: Kazuyoshi Futamura, Takashi Matsumoto, Ryuta Nagai
  • Patent number: 8314599
    Abstract: A DC-DC converter has an error amplifier, a first control unit and an oscillator. The error amplifier amplifies an error voltage between an output voltage and a set voltage, the output voltage being outputted from an inductance element by feeding an input voltage to an inductance element in a predetermined cycle. The first control unit controls the output voltage to a set voltage by causing a switching operation of a switch element in response to an output of the error amplifier, the switch element forming a path for input voltage feed to the inductance. The oscillator generates a periodical signal at the time of switching the switch element. The oscillator handles an oscillation cycle as a short cycle in comparison to any prior cycles, in response to a drop in the output voltage from the set voltage by an amount equivalent to a first voltage value or more.
    Type: Grant
    Filed: June 5, 2009
    Date of Patent: November 20, 2012
    Assignee: Fujitsu Semiconductor Limited
    Inventor: Ryuta Nagai
  • Publication number: 20120025797
    Abstract: A control circuit for controlling a power supply including a first switch and a second switch coupled in series between a first potential and a second potential. The control circuit includes a detection circuit that detects a magnitude relation of a voltage value at a node between the first and second switches and a reference value during a period in which the first switch and the second switch are inactivated. The detection circuit generates a control signal corresponding to the magnitude relation. A regulation circuit regulates a switching timing of the second switch in response to the control signal to decrease a difference between the voltage value at the node and the reference value.
    Type: Application
    Filed: April 15, 2011
    Publication date: February 2, 2012
    Applicant: FUJITSU SEMICONDUCTOR LIMITED
    Inventors: Kazuyoshi FUTAMURA, Takashi MATSUMOTO, Ryuta NAGAI
  • Patent number: 7956586
    Abstract: To provide a control circuit and control method of a step-up/step-down type DC-DC converter capable of realizing high efficiency. In a state (1), a terminal Tx of a choke coil L1 is connected to an input terminal Tin, and a terminal Ty is connected to a reference potential. In a state (2), the terminal Tx is connected to the reference potential, and the terminal Ty is connected to an output terminal Tout. In the state (3), the terminal Tx is connected to the input terminal Tin, and the terminal Ty is connected to the output terminal Tout. A first period operation TO1 is constituted by the states (1) and (2), and a second period operation TO2 is constituted by the states (1) and (3). A second period T2, in which the second period operation TO2 is performed, is a value n times as long as a first period T1, in which the first period operation TO1 is performed. In the second period operation TO2, the state (1) is switched to the state (3) so that an increasing slope of an inductor current IL is reduced.
    Type: Grant
    Filed: June 15, 2007
    Date of Patent: June 7, 2011
    Assignee: Fujitsu Semiconductor Limited
    Inventors: Ryuta Nagai, Takashi Matsumoto, Koichi Inatomi
  • Patent number: 7936156
    Abstract: A first power supply line and having a first conductivity type a second transistor coupled between the first transistor and a second power supply line, and having the first conductivity type an output unit driving a first control signal causing the first transistor to become conductive, based on a drive voltage, and outputting the first control signal to the first transistor and a boot strap circuit including a capacitor having a first end coupled to a node of the first transistor and the second transistor and supplying the output unit with the drive voltage based on the capacitor, wherein an electric potential of the first end is reduced before the first transistor becomes conductive.
    Type: Grant
    Filed: June 10, 2008
    Date of Patent: May 3, 2011
    Assignee: Fujitsu Semiconductor Limited
    Inventors: Morihito Hasegawa, Takashi Matsumoto, Ryuta Nagai, Shoji Tajiri
  • Patent number: 7916503
    Abstract: According to one aspect of the invention, a DC-DC converter including a soft-start function of a soft start in response to a soft-start signal, comprises: a detection circuit that detects whether the soft-start signal is active at an end of a soft-start operation; and an output voltage control circuit that controls an output voltage based on detection result of the detection circuit.
    Type: Grant
    Filed: March 26, 2008
    Date of Patent: March 29, 2011
    Assignee: Fujitsu Semiconductor Limited
    Inventors: Morihito Hasegawa, Takashi Matsumoto, Ryuta Nagai
  • Patent number: 7843179
    Abstract: To provide a control circuit for a synchronous rectifier-type DC-DC converter, a synchronous rectifier-type DC-DC converter and a control method thereof in which, in a light load state and a no-load state, an output voltage can be dropped to thus prevent an overshoot state from continuing.
    Type: Grant
    Filed: November 9, 2007
    Date of Patent: November 30, 2010
    Assignee: Fujitsu Semiconductor Limited
    Inventors: Morihito Hasegawa, Takashi Matsumoto, Ryuta Nagai
  • Patent number: 7821236
    Abstract: A DC-DC converter reducing reverse current and maintaining high conversion efficiency under a light load. The DC-DC converter perform pulse width modulation (PWM) or pulse frequency modulation (PFM) and includes a drive control circuit generating a first drive signal and a second drive signal activating and inactivating a first transistor and a second transistor in a complementary manner. A reversed flow detection circuit detects current flowing to the second transistor and generates a detection signal controlling activation and inactivation of the second transistor. A detection signal invalidation circuit, coupled to the reversed flow detection circuit and the drive control circuit, receiving an operation switch signal and invalidating the detection signal in response to the operation switch signal during at least a certain period of the PWM.
    Type: Grant
    Filed: November 9, 2007
    Date of Patent: October 26, 2010
    Assignee: Fujitsu Semiconductor Limited
    Inventors: Morihito Hasegawa, Takashi Matsumoto, Ryuta Nagai
  • Patent number: 7733074
    Abstract: To provide a control circuit of a current mode DC-DC converter, a current mode DC-DC converter and a control method thereof having excellent high-speed responsiveness with respect to fluctuations in output voltage. The control circuit of the current mode DC-DC converter serves as a DC-DC converter 1 that controls a peak value of a coil current and comprises a window comparator that detects whether an output voltage VOUT is within a predetermined voltage range including a target voltage, and a peak current setting unit that sets a peak current setting value of a coil current to a lower limit value or an upper limit value in response to a high or low voltage level of the output voltage VOUT, in the case that the output voltage VOUT is not within the predetermined voltage range including the target voltage.
    Type: Grant
    Filed: November 8, 2007
    Date of Patent: June 8, 2010
    Assignee: Fujitsu Microelectronics Limited
    Inventors: Morihito Hasegawa, Takashi Matsumoto, Ryuta Nagai
  • Publication number: 20090302817
    Abstract: A DC-DC converter has an error amplifier, a first control unit and an oscillator. The error amplifier amplifies an error voltage between an output voltage and a set voltage, the output voltage being outputted from an inductance element by feeding an input voltage to an inductance element in a predetermined cycle. The first control unit: controls the output voltage to a set voltage by causing a switching operation of a switch element in response to an output of the error amplifier, the switch element forming a path for input voltage feed to the inductance. The oscillator generates a periodical signal at the time of switching the switch element. The oscillator handles an oscillation cycle as a short cycle in comparison to any prior cycles, in response to a drop in the output voltage from the set voltage by an amount equivalent to a first voltage value or more.
    Type: Application
    Filed: June 5, 2009
    Publication date: December 10, 2009
    Applicant: FUJITSU MICROELECTRONICS LIMITED
    Inventor: Ryuta NAGAI
  • Publication number: 20080303500
    Abstract: A first power supply line and having a first conductivity type a second transistor coupled between the first transistor and a second power supply line, and having the first conductivity type an output unit driving a first control signal causing the first transistor to become conductive, based on a drive voltage, and outputting the first control signal to the first transistor and a boot strap circuit including a capacitor having a first end coupled to a node of the first transistor and the second transistor and supplying the output unit with the drive voltage based on the capacitor, wherein an electric potential of the first end is reduced before the first transistor becomes conductive.
    Type: Application
    Filed: June 10, 2008
    Publication date: December 11, 2008
    Applicant: FUJITSU LIMITED
    Inventors: Morihito Hasegawa, Takashi Matsumoto, Ryuta Nagai, Shoji Tajiri
  • Publication number: 20080238394
    Abstract: According to one aspect of the invention, a DC-DC converter including a soft-start function of a soft start in response to a soft-start signal, comprises: a detection circuit that detects whether the soft-start signal is active at an end of a soft-start operation; and an output voltage control circuit that controls an output voltage based on detection result of the detection circuit.
    Type: Application
    Filed: March 26, 2008
    Publication date: October 2, 2008
    Applicant: FUJITSU LIMITED
    Inventors: Morihito HASEGAWA, Takashi MATSUMOTO, Ryuta NAGAI
  • Publication number: 20080136383
    Abstract: A DC-DC converter reducing reverse current and maintaining high conversion efficiency under a light load. The DC-DC converter perform pulse width modulation (PWM) or pulse frequency modulation (PFM) and includes a drive control circuit generating a first drive signal and a second drive signal activating and inactivating a first transistor and a second transistor in a complementary manner. A reversed flow detection circuit detects current flowing to the second transistor and generates a detection signal controlling activation and inactivation of the second transistor. A detection signal invalidation circuit, coupled to the reversed flow detection circuit and the drive control circuit, receiving an operation switch signal and invalidating the detection signal in response to the operation switch signal during at least a certain period of the PWM.
    Type: Application
    Filed: November 9, 2007
    Publication date: June 12, 2008
    Applicant: FUJITSU LIMITED
    Inventors: Morihito Hasegawa, Takashi Matsumoto, Ryuta Nagai
  • Publication number: 20080111531
    Abstract: To provide a control circuit for a synchronous rectifier-type DC-DC converter, a synchronous rectifier-type DC-DC converter and a control method thereof in which, in a light load state and a no-load state, an output voltage can be dropped to thus prevent an overshoot state from continuing.
    Type: Application
    Filed: November 9, 2007
    Publication date: May 15, 2008
    Applicant: FUJITSU LIMITED
    Inventors: Morihito Hasegawa, Takashi Matsumoto, Ryuta Nagai
  • Publication number: 20080111530
    Abstract: To provide a control circuit of a current mode DC-DC converter, a current mode DC-DC converter and a control method thereof having excellent high-speed responsiveness with respect to fluctuations in output voltage. The control circuit of the current mode DC-DC converter serves as a DC-DC converter 1 that controls a peak value of a coil current and comprises a window comparator that detects whether an output voltage VOUT is within a predetermined voltage range including a target voltage, and a peak current setting unit that sets a peak current setting value of a coil current to a lower limit value or an upper limit value in response to a high or low voltage level of the output voltage VOUT, in the case that the output voltage VOUT is not within the predetermined voltage range including the target voltage.
    Type: Application
    Filed: November 8, 2007
    Publication date: May 15, 2008
    Applicant: FUJITSU LIMITED
    Inventors: Morihito Hasegawa, Takashi Matsumoto, Ryuta Nagai
  • Publication number: 20070290667
    Abstract: To provide a control circuit and control method of a step-up/step-down type DC-DC converter capable of realizing high efficiency. In a state (1), a terminal Tx of a choke coil L1 is connected to an input terminal Tin, and a terminal Ty is connected to a reference potential. In a state (2), the terminal Tx is connected to the reference potential, and the terminal Ty is connected to an output terminal Tout. In the state (3), the terminal Tx is connected to the input terminal Tin, and the terminal Ty is connected to the output terminal Tout. A first period operation TO1 is constituted by the states (1) and (2), and a second period operation TO2 is constituted by the states (1) and (3). A second period T2, in which the second period operation TO2 is performed, is a value n times as long as a first period T1, in which the first period operation TO1 is performed. In the second period operation TO2, the state (1) is switched to the state (3) so that an increasing slope of an inductor current IL is reduced.
    Type: Application
    Filed: June 15, 2007
    Publication date: December 20, 2007
    Inventors: Ryuta Nagai, Takashi Matsumoto