US Patent 7461365 Increased effective flip-flop density in a structured ASIC

An H-tree is formed in a conducting layer over a base array of a structured ASIC, an H-tree being a predefined constraint imposed on ad hoc circuit designs adapted to make use of the base array and H-tree. The endpoints of the H-tree are formed at or near sequential elements. When the H-tree is used as part of a clock structure, clock skew to the sequential elements is minimized as is the consumption of routing resources for forming the clock structure. When a pulse generator is coupled to the H-tree, each individual flip-flop of a plurality of flip-flops can be emulated with an individual latch, thereby increasing effective flip-flop density.