Technology Mapping for Circuits with Simple Cells

This paper presents two main contributions toward efficient VLSI circuits mapped with simple cells: (1) a complete synthesis flow to provide good-quality circuits mapped only with simple cells; and (2) an area-oriented, level-aware buffering algorithm based on inverter trees to fix cell fanout violations. We show that efficient implementations in terms of inverter count, transistor count, area, power and delay can be generated from circuits with a reduced number of both simple cells and inverters, combined with XOR/XNOR-based optimizations. The proposed buffering algorithm can handle all unfeasible fanout occurrences, while (i) optimizing the number of added inverters; and (ii) assigning cells to the inverter tree based on their level criticality. When comparing with academic and commercial approaches, we are able to simultaneously reduce the average number of inverters, transistors, area, power dissipation and delay up to 48%, 4%, 8%, 14%, and 16%, respectively.