Patents by Inventor David W. Blum

David W. Blum 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: 6426660
    Abstract: A duty-cycle correction circuit corrects a clock with arbitrary duty-cycle to a 50% duty-cycle clock, with its original frequency. The device acts to translate a non-50% duty-cycle clock to an accurate 50% duty-cycle clock by utilizing a divide-by-2 frequency divider and a multiply-by-2 clock doubler to achieve conversion. The duty-cycle correction circuit increases the translation back to its original frequency while using an analog negative feedback to maintain an accurate 50% duty cycle.
    Type: Grant
    Filed: August 30, 2001
    Date of Patent: July 30, 2002
    Assignee: International Business Machines Corporation
    Inventors: Shiu C. Ho, David W. Blum
  • Patent number: 5757218
    Abstract: A duty cycle correction circuit that facilitates correction of clock signal duty cycles, including correcting for errors introduced by intervening devices in the clock signal distribution network. The duty cycle correction circuit of the preferred embodiment comprises a clock chopper circuit, a duty cycle comparator circuit, and a control circuit. The duty cycle comparator circuit compares the duty cycle of the clock signal with the duty cycle of a reference signal. The control circuit adjusts the clock chopper circuit based upon the duty cycle comparison, resulting in an output with a corrected duty cycle.
    Type: Grant
    Filed: March 12, 1996
    Date of Patent: May 26, 1998
    Assignee: International Business Machines Corporation
    Inventor: David W. Blum
  • Patent number: 5418484
    Abstract: This is a detector system comprised of a differential driver circuit, a driver output stage and splitter circuit and a multiplexor. The driver circuit employs a bridge circuit that converts input logic voltages to lower voltage differential outputs by utilizing a pair of current switch transistors coupled to the bridge circuit. The bridge circuit is comprised of cross coupled transistors whose inputs are coupled to matched true and complement input logic voltages that swing between zero volts and the power supply voltage. The bridge transistors convert the differential logic input voltage swings to smaller values that are compatible with driving the splitter and multiplexor circuits coupled thereto. The driver circuit and the splitter circuit share the driver output transistors which are arranged in parallel pairs.
    Type: Grant
    Filed: July 1, 1993
    Date of Patent: May 23, 1995
    Assignee: International Business Machines Corp.
    Inventors: David W. Blum, John E. Gersbach