PROGRAMMABLE LOGIC DEVICE WITH REGIONAL AND UNIVERSAL SIGNAL ROUTING

摘要

A programmable logic device having a plurality of logic cells (151-15N) arranged in groups defining separate logic regions (111-11N), both regional (191-19N) and multi-regional (13) bus lines, and a crosspoint switch matrix (37) which serves only to route signals from bus lines (391-39J and 401-40L) to inputs of the logic cells (311-31J) without logically combining two or more of the bus signals, i.e. without forming product terms. Rather, all logic is carried out by the logic cells (311-31J) themselves. In particular, the switch matrix (37) is constructed so that each bus line (391-39J and 401-40L) can connect to one or more logic cell inputs, but each logic cell input can meaningfully connect to only one bus line without shorting. In one embodiment, each logic cell (311-31J) feeds one logic signal back (411-41J) to a regional bus line (191) and can potentially feed back another logic signal through its region's universal select matrix (47) to a universal bus line (13). The select matrix (47) connects a subset of the region's potential feedback signals to the universal bus (13).