Patents by Inventor John R. Ollis

John R. Ollis 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: 4430641
    Abstract: A circuit including a conventional digital-to-analog converter (DAC) and a charge pump for producing an analog representation of an input waveform defined by an input digital bit stream, the analog representation being relatively free of spurious aberrations usually present in the output of a conventional DAC. The charge pump and an associated integrator are used to produce a first approximation of the input waveform and the DAC and an associated detuned slew-rate filter are used to maintain the first approximation in long-term conformance with a more accurate second approximation. Spurious aberrations in the second approximation are integrated over several steps of the input bit stream, thereby minimizing their adverse impact on the relatively true first approximation.
    Type: Grant
    Filed: May 11, 1981
    Date of Patent: February 7, 1984
    Assignee: Tektronix, Inc.
    Inventors: Bruce K. Baur, John R. Ollis