Patents by Inventor David R. Wellard

David R. Wellard 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: 5012244
    Abstract: An oscillation detect and reset circuit is provided for an analog modulator that includes a first stage of integration having a single ended differential amplifier (32) which is connected to the input of three stages of subsequent integration (40), (42) and (44), in a cascaded configuration. The output of the last stage of integration (44) is connected to the input of a one-bit quantizer (48). The output of the one-bit quantizer (48) is connected to the input of a current (50) feedback, which is connected between a summing node (36) and a negative voltage supply. The summing node (36) sums the current feedback with an input voltage for input to the amplifier (32). Switches (52), (54) and (56) are provided across the inputs and outputs of the integration stages (40), (42) and (44), respectively. The sensing of an unstable condition on the output of second stage of integration (40) is detected by oscillation detect comparators (60) and (62) to initiate a count cycle in a five-bit counter (66).
    Type: Grant
    Filed: October 27, 1989
    Date of Patent: April 30, 1991
    Assignee: Crystal Semiconductor Corporation
    Inventors: David R. Wellard, Donald A. Kerth, Bruce P. Del Signore, Eric J. Swanson