Patent ID: 7218133

Claim:
A programmable logic device comprising: a function block within a first row of function blocks comprising a carry input terminal; and a selection unit comprising a first input terminal, a second input terminal, and an output terminal, the first input terminal coupled to a carry output terminal of a function block within a second row of function blocks, the second input terminal coupled to a carry output terminal of a function block within a third row of function blocks, and the output terminal coupled to the carry input terminal of the function block within the first row of function blocks, wherein the second row of function blocks is directly adjacent to the first row of function blocks in a direction that logic is shifted if redundancy is engaged and the third row of function blocks is directly adjacent to the second row of function blocks in the direction that logic is shifted if redundancy is engaged, and if the second row of function blocks is defective then the selection unit outputs a signal received on the second input terminal of the selection unit, otherwise, the selection unit outputs a signal received on the first input terminal of the selection unit.