Patents by Inventor David W. Chan

David W. Chan 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: 5334959
    Abstract: An improved 180.degree. phase shifter bit that uses embedded switches to selectively connect the RF input and RF output to a loosely coupled transmission line segment and a pi section of transmission line. A hybrid coupler is selected having characteristic impedance of less than 50 ohms and having coupling of less than -3 db. The result of this coupling choice is extremely low insertion loss. The resultant impedance mismatch is compensated for by providing oversized field effect transistors that allow RF signal in both the grounded coupler and the pi section of transmission lines that are 180.degree. out of phase. The RF signal present in both the coupler and pi section of the transmission line results in a cancellation effect allowing recovery of the input/output impedance over an approximately one octave bandwidth.
    Type: Grant
    Filed: April 15, 1993
    Date of Patent: August 2, 1994
    Assignee: Westinghouse Electric Corporation
    Inventors: David M. Krafcsik, David W. Chan