Patents by Inventor Roger A. Mao

Roger A. Mao 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: 4594577
    Abstract: An integrated circuit digital to analog converter comprised of MOS current mirrors and utilizing additional MOS devices to provide transmission gates and control means. Each transmission gate 36 is connected to a source of digital data to be converted and the mirroring device for each transmission gate 36 has a channel width with some predetermined proportional relationship to the channels of input transistors 12 and mirroring output MOS transistors 14 to 44 with the input transistor 12 connected to a constant current source, the total output mirroring current of the output mirroring transistors is in quantised analog form and varies according to the cumulative currents from the mirroring MOS transistors as the transistors are activated. The invention may be embodied in linear multiplying, non-linear and companding converters.
    Type: Grant
    Filed: September 24, 1982
    Date of Patent: June 10, 1986
    Assignee: American Microsystems, Inc.
    Inventor: Roger A. Mao
  • Patent number: 4384274
    Abstract: An integrated circuit digital to analog converter comprised of MOS current mirrors and utilizing additional MOS devices to provide transmission gates and control means. Each transmission gate 36 is connected to a source of digital data to be converted and the mirroring device for each transmission gate 36 has a channel width with some predetermined proportional relationship to the channels of input transistors 12 and mirroring output MOS transistors 14 to 44 with the input transistor 12 connected to a constant current source, the total output mirroring current of the output mirroring transistors is in quantized analog form and varies according to the cumulative currents from the mirroring MOS transistors as the transistors are activated. The invention may be embodied in linear multiplying, non-linear and companding converters.
    Type: Grant
    Filed: September 2, 1980
    Date of Patent: May 17, 1983
    Assignee: American Microsystems, Inc.
    Inventor: Roger A. Mao