Patents by Inventor Roger N. Langmaid

Roger N. Langmaid 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).

  • Weighted random pattern testing apparatus and method
    Patent number: 4745355
    Abstract: A method and apparatus for testing very large scale integrated circuit devices, most particularly Level Sensitive Scan Design (LSSD) devices, by applying differently configured sequences of pseudo-random patterns in parallel to each of the input terminals of the device under test, collecting the output responses from each of the output terminals in parallel, combining these outputs to obtain a signature which is a predetermined function of all of the sequences of parallel outputs and comparing the test signature with a known good signature obtained by computer simulation. The input test stimuli are further altered in a predetermined fashion as a function of the structure of the device to be tested, to individually weight the inputs in favor of more or less binary ones or zeros.
    Type: Grant
    Filed: May 11, 1987
    Date of Patent: May 17, 1988
    Assignee: International Business Machines Corporation
    Inventors: Edward B. Eichelberger, Roger N. Langmaid, Eric Lindbloom, Franco Motika, John L. Sinchak, John A. Waicukauski
  • Weighted random pattern testing apparatus and method
    Patent number: 4687988
    Abstract: A method and apparatus for testing very large scale integrated circuit devices, most particularly Level Sensitive Scan Design (LSSD) devices, by applying differently configured sequences of pseudo-random patterns in parallel to each of the input terminals of the device under test, collecting the output responses from each of the output terminals in parallel, combining these outputs to obtain a signature which is a predetermined function of all of the sequences of parallel outputs and comparing the test signature with a known good signature obtained by computer simulation. The input test stimuli are further altered in a predetermined fashion as a function of the structure of the device to be tested, to individually weight the inputs in favor of more or less binary ones or zeros.
    Type: Grant
    Filed: June 24, 1985
    Date of Patent: August 18, 1987
    Assignee: International Business Machines Corporation
    Inventors: Edward B. Eichelberger, Roger N. Langmaid, Eric Lindbloom, Franco Motika, John L. Sinchak, John A. Waicukauski