Method and Apparatus for Improving Efficiency of Programmable Logic Circuit Using Cascade Configuration

An integrated circuit ("IC") device capable of programmably performing user selected functions is disclosed. The IC device, in one embodiment, includes multiple input output ("I/O") blocks, programmable interconnection blocks ("PIBs"), and programmable logic blocks ("PLBs"). While the I/O blocks can be selectively coupled to one of I/O pads, the PIB blocks can be selectively coupled to at least a portion of the I/O blocks. Each of the PLBs, in one aspect, is configured to have at least two programmable look-up tables ("LUTs"). The programmable LUTs are connected in a cascade configuration via a dedicated programmable wire ("DPW").