Patents by Inventor Yoko Kawasumi

Yoko Kawasumi 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).

  • Wide lock range phase locked loop and method of operation
    Patent number: 7023283
    Abstract: In a phase locked loop type frequency synthesizer including a phase/frequency comparator for receiving an input signal, a charge pump circuit, a loop filter for generating a control voltage, a voltage control oscillator block including a plurality of voltage controlled oscillators controlled by the control voltage, and a frequency divider formed by a fixed frequency divider and a programmable frequency divider, a selecting circuit selects and activates only one of the voltage controlled oscillators, and counts a number of output pulses of the first frequency divider within a predetermined number of output pulses of the input signal while applying a bias voltage to the loop filter. Thus, the one of the voltage controlled oscillators being selected so that the number of the output pulses of the first frequency divider is brought close to an optimum value.
    Type: Grant
    Filed: February 25, 2004
    Date of Patent: April 4, 2006
    Assignee: NEC Compound Semiconductor Devices, Ltd.
    Inventors: Yoko Kawasumi, Akira Kuwano, Yoshitaka Murata
  • Wide lock range phase locked loop type frequency synthesizer capable of enhancing precision of phase/frequency comparator without increasing lockup time and its method for selecting oscillation frequency
    Publication number: 20040164811
    Abstract: In a phase locked loop type frequency synthesizer including a phase/frequency comparator for receiving an input signal, a charge pump circuit, a loop filter for generating a control voltage, a voltage control oscillator block including a plurality of voltage controlled oscillators controlled by the control voltage, and a frequency divider formed by a fixed frequency divider and a programmable frequency divider, a selecting circuit selects and activates only one of the voltage controlled oscillators, and counts a number of output pulses of the first frequency divider within a predetermined number of output pulses of the input signal while applying a bias voltage to the loop filter. Thus, the one of the voltage controlled oscillators being selected so that the number of the output pulses of the first frequency divider is brought close to an optimum value.
    Type: Application
    Filed: February 25, 2004
    Publication date: August 26, 2004
    Inventors: Yoko Kawasumi, Akira Kuwano, Yoshitaka Murata