Patents by Inventor Tam-Thanh C. Buu

Tam-Thanh C. Buu 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).

  • Automatically controlled varactor tuned matching networks for a crystal filter
    Patent number: 5216392
    Abstract: A crystal filter network comprises at least one variable impedance network (103a, 103b), at least one crystal filter (103c), and a control circuit (110). Each variable impedance network (103a, 103b) has a control terminal, a first terminal (37, 39), and a second terminal (38, 40) for connecting a first impedance (113) coupled to the first terminal (37), to a second impedance coupled to the second terminal (38). The crystal filter (103c) is coupled to at least one of the first and second terminals. Coupled to the control terminal, the control circuit (110) electrically varies (V.sub.1 and V.sub.2) the variable impedance network (103a, 103b) to provide a predetermined impedance characteristic to the crystal filter network (103c).
    Type: Grant
    Filed: July 5, 1991
    Date of Patent: June 1, 1993
    Assignee: Motorola, Inc.
    Inventors: Randall S. Fraser, Tam-Thanh C. Buu, Charles R. Ruelke