Patents by Inventor David John Johnston

David John Johnston 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).

  • Voltage controlled oscillators
    Patent number: 6683509
    Abstract: A frequency synthesiser comprises a voltage controlled oscillator, VCO, having means for fine tuning the oscillator frequency and switchable capacitive elements for coarse tuning the oscillator frequency. First comparison means are provided for comparing the frequency and phase of the output of the VCO or a signal derived therefrom with that of a reference frequency signal to provide an error signal, the error signal being provided to said means for fine tuning the oscillator frequency. Second comparison means are provided for comparing the error signal against one or more reference values and a control means receives the result of the comparison from the second comparison means and switches said switchable capacitive elements on and off in dependence upon the result so as to coarse tune the oscillator frequency.
    Type: Grant
    Filed: August 20, 2002
    Date of Patent: January 27, 2004
    Assignee: Zarlink Semiconductor Limited
    Inventors: Richard Albon, David John Johnston
  • Voltage controlled oscillators
    Publication number: 20030048145
    Abstract: A frequency synthesiser comprises a voltage controlled oscillator, VCO, having means for fine tuning the oscillator frequency and switchable capacitive elements for coarse tuning the oscillator frequency. First comparison means are provided for comparing the frequency and phase of the output of the VCO or a signal derived therefrom with that of a reference frequency signal to provide an error signal, the error signal being provided to said means for fine tuning the oscillator frequency. Second comparison means are provided for comparing the error signal against one or more reference values and a control means receives the result of the comparison from the second comparison means and switches said switchable capacitive elements on and off in dependence upon the result so as to coarse tune the oscillator frequency.
    Type: Application
    Filed: August 20, 2002
    Publication date: March 13, 2003
    Inventors: Richard Albon, David John Johnston