Clustered field programmable gate array architecture

Abstract

A logic cluster for a field programmable gate array integrated circuit device is disclosed. The cluster comprises a plurality of functional blocks and three levels of routing multiplexers. External signals enter the logic cluster primarily at the third level multiplexers with a few signals entering at the second level. Combinational outputs are fed back into the first and second level multiplexers while sequential outputs are fed back into the third level multiplexers. The logic function generators have permutable inputs with varying propagation delays. Routing signals between the first and second level multiplexers are grouped into speed classes and coupled to first level multiplexers associated with different logic function generators according to their speed class. Second and third level multiplexers are organized into groups such that routing signals between the second and third level multiplexers can be localized within the area occupied by the group. Groups are pitch matched to logic function generators to optimize and modularize area. Provision is made for global and local control of the sequential elements.