Patents by Inventor Andrew D. Ingraham

Andrew D. Ingraham 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: 5115455
    Abstract: Data can be accurately transmitted between two subsystems in a synchronous system even if the clock skew or propagation delay between the two subsystems is greater than one clock cycle time. The source and destination subsystems are initialized to ensure synchronous operation. The source subsystem transmits data and a forwarded clock to the destination subsystem. The forwarded clock is passed through a delay device to introduce a one-half cycle delay into the forwarded clock timing. Data is captured in three state devices arranged in parallel to eliminate minimum delay requirements and to expand data valid time. The captured data is then aligned to the destination subsystem's clock by controlling a multiplexer which selects the proper signal at its input to pass to the input of a second state device coupled to its output. The data selected is then clocked into the second state device under the control of the distination subsystem's clock, thus aligning the received data with the destination subsystem's clock.
    Type: Grant
    Filed: June 29, 1990
    Date of Patent: May 19, 1992
    Assignee: Digital Equipment Corporation
    Inventors: William A. Samaras, David T. Vaughan, Andrew D. Ingraham
  • Patent number: 4979190
    Abstract: Data can be accurately transmitted between two subsystems even if the clock skew between the two subsystems is larger than one clock cycle by the method of the invention. In one embodiment data is loaded into N state devices in the sending subsystem while the receiver recovers data from the sending state devices in rotation with an N input multiplexer. Another embodiment forwards a clock signal from the sending subsystem along with a data vector of N state signals for recovery by a pair of state devices capturing data on the rising and falling edges of the forwarded clock. A further embodiment achieves double bandwidth by forwarding two clock signals.
    Type: Grant
    Filed: January 30, 1989
    Date of Patent: December 18, 1990
    Assignee: Digital Equipment Corporation
    Inventors: David J. Sager, Leon D. Hesch, Andrew D. Ingraham, William A. Samaras
  • Patent number: 4811364
    Abstract: Data can be accurately transmitted between two subsystems even if the clock skew between the two subsystems is larger than one clock cycle by the method of the invention. In one embodiment data is loaded into N state devices in the sending subsystem while the receiver recovers data from the sending state devices in rotation with an N input multiplexer. Another embodiment forwards a clock signal from the sending subsystem along with a data vector of N state signals for recovery by a pair of state devices capturing data on the rising and falling edges of the forwarded clock. A further embodiment achieves double bandwidth by forwarding two clock signals.
    Type: Grant
    Filed: April 1, 1988
    Date of Patent: March 7, 1989
    Assignee: Digital Equipment Corporation
    Inventors: David J. Sager, Leon D. Hesch, Andrew D. Ingraham, William A. Samaras