A carry chain in a logic array block includes a first path connecting a first series of logic elements in the logic array block, where the logic elements in the first series is a subset of the set of logic elements in the logic array block. The carry chain also includes a second path connecting a second...http://www.google.com/patents/US7205791?utm_source=gb-gplus-sharePatent US7205791 - Bypass-able carry chain in a programmable logic device
