Patents Represented by Attorney Patrick T. Bever, Hoffman & Harms Bever, Esq.
  • Patent number: 6150838
    Abstract: A logic/memory circuit (LMC) utilized in a configurable logic block (CLB) of a programmable logic device (PLD) that implements an eight-input lookup table (LUT) using an array of programmable elements arranged in rows and columns. A decoder is used to read bit values from one column (e.g., sixteen programmable elements) of the array. In one embodiment, a separate read bit line is provided to facilitate faster read operations. A sixteen-to-one multiplexer/demultiplexer circuit is used to pass selected bit values to an output terminal. The array of programmable elements is programmable both from configuration lines during a configuration mode, and by data transmitted on the interconnect resources through the multiplexer/demultiplexer circuit. In one embodiment, the programmable elements of the array are connected in pairs to product term generation circuitry. Product terms generated by the product term circuitry are passed to a macrocell circuit to perform programmable array logic (PAL) logic operations.
    Type: Grant
    Filed: February 25, 1999
    Date of Patent: November 21, 2000
    Assignee: Xilinx, Inc.
    Inventors: Ralph D. Wittig, Sundararajarao Mohan, Richard A. Carberry