ThunderBird: a complete standard cell layout package

The generalized standard cell layout style handled by ThunderBird is characterized by horizontal rows of standard cells with pads placed around the periphery of the chip. Furthermore, macro blocks may be present on the chip. The standard cells are permitted to have varying heights. The two key components of ThunderBird are TimberWolf3.2, a standard cell placement and global routing package, and the YACR II channel router. The placement and global routing proceed over three distinct stages: (1) cell placement for minimum interconnect length, (2) insertion of feedthrough cells or location of built-in feeds, and another interconnect-length minimization; and (3) local changes in placement to reduce the number of wiring tracks required. This channel router features a 100% routing completion rate while usually routing each channel using a number of tracks equal to a density of the channel. Results on industrial circuits versus numerous automatic and manual layout methods showed that ThunderBird yielded area savings ranging from 15 to 75%. >