Patents by Inventor Simon C. F. Leung

Simon C. F. Leung 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: 5699387
    Abstract: A phase locked loop is comprised of a phase-frequency detector for providing to a charge pump up and down pulse signals having pulse widths proportional to phase differences between a pair of signals applied thereto, apparatus for introducing a relative phase difference between a first clock signal and a second signal to provide the pair of signals, the second signal being synchronized with an output signal of the loop, apparatus for providing a third up or down signal to the charge pump offsetting the effect of the introduced phase difference, and apparatus for obtaining a loop control voltage from the charge pump.
    Type: Grant
    Filed: June 23, 1993
    Date of Patent: December 16, 1997
    Assignee: ATI Technologies Inc.
    Inventors: Jim M. N. Seto, Roger P. Colbeck, Raymond Chau, Simon C. F. Leung
  • Patent number: 5459653
    Abstract: A voltage to current converter is formed of a first current steering mirror which includes first binary weighted current mirror transistors and receives an input voltage signal and converts it to an output current. The converter also is formed of a second current mirror which generates a selectable output current, the second current mirror being formed of second binary weighted current mirror transistors. The output currents of the first current steering mirror and second current mirror are added and the sum is provided to the control input of a current controlled oscillator which can be used in a phase locked loop.
    Type: Grant
    Filed: June 23, 1993
    Date of Patent: October 17, 1995
    Assignee: ATI Technologies Inc.
    Inventors: Jim M. N. Seto, Roger P. Colbeck, Raymond Chau, Simon C. F. Leung