Patents by Inventor Jack Siu Cheung Lo

Jack Siu Cheung Lo 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: 6864727
    Abstract: An integrated clock doubler and polarity control circuit are described. The circuit provides high speed response between an input signal and an output signal, achieving clock doubling by passing the input signal through a delay circuit and using the output of the delay circuit to select between two paths for inverting or not inverting the input signal to produce the output signal. In one embodiment, the inverting path is a CMOS inverter with input terminal receiving the input signal, output terminal providing the output signal, and power terminals controlled by the delay circuit.
    Type: Grant
    Filed: January 10, 2003
    Date of Patent: March 8, 2005
    Assignee: Xilinx, Inc.
    Inventors: Jack Siu Cheung Lo, Shankar Lakkapragada, Shi-dong Zhou
  • Patent number: 6744289
    Abstract: A clock divider circuit that adds little additional delay on the clock path. Each rising and falling edge of an input clock signal triggers a pulse from a pulse generator circuit. These pulses are passed to a control circuit. True and complement versions of the input clock signal are provided to a multiplexer circuit. Under the direction of the control circuit, the multiplexer circuit passes selected rising edges of the true clock signal, and selected falling edges of the complement clock signal, to an output clock terminal of the clock divider circuit. When neither the true nor the complement clock signal is passed by the multiplexer, a keeper circuit retains the value already present at the output clock terminal.
    Type: Grant
    Filed: July 10, 2002
    Date of Patent: June 1, 2004
    Assignee: Xilinx, Inc.
    Inventors: Andy T. Nguyen, Jack Siu Cheung Lo
  • Publication number: 20030102894
    Abstract: An integrated clock doubler and polarity control circuit are described. The circuit provides high speed response between an input signal and an output signal, achieving clock doubling by passing the input signal through a delay circuit and using the output of the delay circuit to select between two paths for inverting or not inverting the input signal to produce the output signal. In one embodiment, the inverting path is a CMOS inverter with input terminal receiving the input signal, output terminal providing the output signal, and power terminals controlled by the delay circuit.
    Type: Application
    Filed: January 10, 2003
    Publication date: June 5, 2003
    Applicant: Xilinx, Inc.
    Inventors: Jack Siu Cheung Lo, Shankar Lakkapragada, Shi-Dong Zhou
  • Publication number: 20030048118
    Abstract: A clock divider circuit that adds little additional delay on the clock path. Each rising and falling edge of an input clock signal triggers a pulse from a pulse generator circuit. These pulses are passed to a control circuit. True and complement versions of the input clock signal are provided to a multiplexer circuit. Under the direction of the control circuit, the multiplexer circuit passes selected rising edges of the true clock signal, and selected falling edges of the complement clock signal, to an output clock terminal of the clock divider circuit. When neither the true nor the complement clock signal is passed by the multiplexer, a keeper circuit retains the value already present at the output clock terminal.
    Type: Application
    Filed: July 10, 2002
    Publication date: March 13, 2003
    Applicant: Xilinx, Inc.
    Inventors: Andy T. Nguyen, Jack Siu Cheung Lo
  • Patent number: 6456126
    Abstract: An integrated clock doubler and polarity control circuit are described. The circuit provides high speed response between an input signal and an output signal, achieving clock doubling by passing the input signal through a delay circuit and using the output of the delay circuit to select between two paths for inverting or not inverting the input signal to produce the output signal. In one embodiment, the inverting path is a CMOS inverter with input terminal receiving the input signal, output terminal providing the output signal, and power terminals controlled by the delay circuit.
    Type: Grant
    Filed: May 25, 2001
    Date of Patent: September 24, 2002
    Assignee: Xilinx, Inc.
    Inventors: Jack Siu Cheung Lo, Shankar Lakkapragada, Shi-dong Zhou
  • Patent number: 6362669
    Abstract: A power-on reset (POR) circuit that delays de-assertion a POR control signal in an IC device such that, when unstable power levels are detected, the POR control signal is maintained in an asserted condition until the IC device is fully reset. During a start-up phase of the IC device operation, the POR control circuit maintains the POR control signal in the asserted condition for a delay period whose length is determined, in part, by the amount of noise in the applied power. After the internal voltage of the IC device achieves a steady state for a suitable period of time, the POR control circuit de-asserts the POR control signal, thereby initiating configuration of the IC device. Subsequently, if a low power condition is detected, the POR control circuit asserts the POR control signal, and maintains the POR control signal in the asserted condition for a pre-defined delay period after the low-power event is detected, thereby allowing the IC device to fully reset.
    Type: Grant
    Filed: April 10, 2000
    Date of Patent: March 26, 2002
    Assignee: Xilinx, Inc.
    Inventors: Shi-dong Zhou, Jack Siu Cheung Lo