NSP kernel finder - A methodology to find and to build non-series-parallel transistor arrangements

Abstract

The transistor arrangement optimization is an effective possibility to improve logic gates and, consequently, VLSI design. This paper presents a graph-based methodology to determine if an ISOP may be implemented in non-series-parallel (NSP) switch arrangement. The proposed method aims to combine the cubes of such ISOP to build a graph where the vertices represent the cubes and the edges exist whether the vertices have common literals. Hence, if the obtained graph has the same topology of a `bridge' arrangement and each cube has all literals shared through the edges, this ISOP may be efficiently implemented through a NSP transistor network. The experiments were performed over the set of 4-input P-class Boolean functions, and the results were compared to the Moore's catalog. These experiments demonstrate that the proposed method tends to deliver optimal solutions for unate functions. Moreover, the method was able to determine equivalent SP or NSP transistor arrangements in 82.69% of the cases when considering a set of non-unate functions.