Patents by Inventor Raymond M. Caldwell

Raymond M. Caldwell 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).

  • Voltage variable capacitor
    Patent number: 5173835
    Abstract: A voltage variable capacitor (10) has as the base substrate a silicon wafer with a layer of high resistivity semiconductor material on top of the substrate. An insulating layer (16) of a metal oxide having a dielectric constant greater than the dielectric constant of the semiconductors (12), such as zirconium titanate, is formed on top of the high resistivity layer, and a metal electrode (18) is formed on the insulating layer (16). When the electrode is energized, a depletion layer (20) is formed in the high resistivity layer. By varying the voltage applied to the electrode, the capacitance of the device is altered.
    Type: Grant
    Filed: October 15, 1991
    Date of Patent: December 22, 1992
    Assignee: Motorola, Inc.
    Inventors: Kenneth D. Cornett, E. S. Ramakrishnan, Gary H. Shapiro, Raymond M. Caldwell, Wei-Yean Howng