Patents by Inventor James Stuart Irwin

James Stuart Irwin 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: 6065140
    Abstract: Given a target frequency (F.sub.VE), a reference frequency (F.sub.R), an error limit (E.sub.L), and a first divider range (150), a first (R) and a second (N) integer divider value are computed. First, an initial first divider (R) is selected (152). Then, a second divider (N) is computed as equal to the target frequency (F.sub.VE) divided by the reference frequency (F.sub.R) multiplied times the selected first divider (154). Then an error term (E) is computed to quantify the error introduced by using integers as dividers (156). The divider terms are accepted (166) if the error term is less than the error limit (158). Otherwise, a new first integer divider (R) is selected (160), repeating the computation of the second (N) divider (154), the computation of the error (E) term (156), and the test of the error term (E) against a limit as a loop (158). This loop is repeated until either the error term (E) is less than the error (E.sub.
    Type: Grant
    Filed: April 30, 1997
    Date of Patent: May 16, 2000
    Assignee: Motorola, Inc.
    Inventor: James Stuart Irwin
  • Patent number: 5774023
    Abstract: A phase locked loop (PLL) system receiving a reference frequency and generating an output frequency has a charge pump (28), loop filter (38), an N frequency divider (32), an R frequency divider (24), a Voltage Controlled Oscillator (30) and a phase detector (26). The charge pump (28) has a high current output (62) and a low current output (60). The loop filter (38) responsively coupled to the charge pump (28) has a first pole filter that includes a high current first pole filter capacitor (66), a high current first pole damping resistor (70), a low current first pole filter capacitor (64), a low current first pole damping resistor (68), and a first pole filter capacitor (72). A second pole filter can be added that includes a second pole filter capacitor (76), a second pole damping resistor (74), and a feed forward capacitor (78).
    Type: Grant
    Filed: April 30, 1997
    Date of Patent: June 30, 1998
    Assignee: Motorola, Inc.
    Inventor: James Stuart Irwin
  • Patent number: 4121218
    Abstract: An extendable half-wave dipole is capacitively coupled to a driven resonant helical antenna for use as on a hand-held, two-way portable radio, the helix being end fed. The dipole may be mounted adjacent to or collinear with the axis of the helix. The collinear mounting requires non-conductive portions on each end of the dipole. Optimum dimensional and performance characteristics are available without switching.
    Type: Grant
    Filed: August 3, 1977
    Date of Patent: October 17, 1978
    Assignee: Motorola, Inc.
    Inventors: James Stuart Irwin, Francis Robert Steel