A high-density data-path generator with stretchable cells

This paper describes a newly developed module generator for cell-based design which generates a data-path layout comparable to a handcrafted one both in speed and in transistor density. The chip designer enters his schematic data-path diagram using the configurable function block library provided. There is no constraint either in the number of function blocks used, or in how to interconnect them. The data-path generator generates the function blocks, which are components of the data-path, and automatically places and routes them. The configurable function blocks were developed in 0.8-μm double metal CMOS technology. A new cell structure suitable for over the cell routing, called “stretchable cell with access free terminals,” is adopted as a bit-slice element of the data-path generator. This removes the routing region outside the cell for the wiring between function blocks, and a high density layout can be obtained. Also because of the new cell structure, there is no upper limit on the number of tracks per bit. Using this data-path generator, several data-paths were generated with high density of more than 6k Trs./mm²