Patents by Inventor Thomas M. Fredericksen

Thomas M. Fredericksen 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).

  • Double digital-to-analog converter
    Patent number: 4198622
    Abstract: Two digital-to-analog converters are coupled in series across a reference potential source. Each converter includes a resistor ladder and switching tree that permits coupling the output to any single tap on the ladder. A digital word is split into two portions, each one of which operates one switching tree. The converters are weighted in accordance with the word bits applied. The switching tree outputs are combined to produce an analog output related to the reference potential and the digital word.
    Type: Grant
    Filed: December 11, 1978
    Date of Patent: April 15, 1980
    Assignee: National Semiconductor Corporation
    Inventors: Joseph J. Connolly, Jr., Thomas M. Fredericksen, Thomas P. Redfern