Patent ID: 7176716

Claim:
A programmable four input look up table (4LUT) structure adapted for carry logic implementation in an integrated circuit, comprising: a one input look up table (1LUT) structure, said input received in true and compliment levels, said 1LUT structure further comprising a first LUT value input; and a first three input look up table (3LUT) structure, said three inputs received in true and compliment levels, said 3LUT structure further comprising an output; and a first programmable multiplexer (MUX) structure comprised of: a plurality of MUX inputs, one of the MUX inputs coupled to said first 3LUT output, and one of the MUX inputs coupled to a carry-in signal; and a MUX output, said output coupled to said first LUT value input; and a programmable means for said first 3LUT output to couple to said 1LUT input, and for one of the first MUX inputs to couple to said first LUT value input.