Array of configurable logic blocks including cascadable lookup tables

摘要

A programmable integrated circuit includes configurable logic blocks (CLB's), configurable input/output blocks (IOB's) and a configurable interconnect network for providing program-defined routing of signals between the CLB's and IOB's. Each CLB includes a plurality of function lookup tables (LUT's) each defined by a bit storage area and a select means responsive to input signals for selecting a stored bit. The design includes first and second LUT's that share a same plurality of input signals where the output of one of the LUT's is connectable by direct connect means to an input of a further pair of LUT's.