Patents Represented by Attorney, Agent or Law Firm Crosby Heafy
  • Patent number: 6552526
    Abstract: A method and system are provided for increasing the accuracy of AC parametric testing. The invention provides a method of precisely estimating signal propagation delay time in an integrated circuit testing apparatus, wherein a plurality of signal propagation delay time measurements are taken and additional delay times are estimated by linearly interpolating the measured delays. A desired test point (desired output voltage at a given time) is established. Using a sample device, a slope is established on a time vs. voltage plot for a line through the desired test point. Where a desired test point falls between strobe times on a tester, linear extrapolation is used to calculate what voltages must be tested for at the two bracketing strobe times in order to guarantee the desired performance at the desired test point. One or more devices are then tested for the calculated voltages at the corresponding bracketing strobe times.
    Type: Grant
    Filed: May 23, 2000
    Date of Patent: April 22, 2003
    Assignee: Xilinx, Inc.
    Inventors: Mihai G. Statovici, Ronald J. Mack
  • Patent number: 6507860
    Abstract: A system and method are disclosed for providing highly parallel, FFT calculations in a circuit including a plurality of RADIX-2 elements. Partitioned RAM resources allow RADIXes at all stages to have optimal bandwidth memory access. Preferably more memory is made available for early RADIX stages and a “critical” stage. RADIXes within stages beyond the critical stage preferably each need only a single RAM partition, and can therefore simultaneously operate without fighting for memory resources. In a preferred configuration having P RAM partitions and P RADIX stages, the critical stage is stage number log2P, and until the critical stage, only P/2 RADIX elements can simultaneously operate within each stage. After the critical stage, all RADIXes within each stage can simultaneously operate.
    Type: Grant
    Filed: September 26, 2000
    Date of Patent: January 14, 2003
    Assignee: Xilinx, Inc.
    Inventors: Hare K. Verma, Sudip K. Nag