Logic Synthesis of Pass-Gate Logic Circuits with Emerging Ambipolar Technologies

Emerging devices and new ultrascaled silicon transistors have shown disruptive electrical and functional properties that might bring digital hardware to the next level. The key issue today concerns their integration. Even though the classical complementary logic style is the most intuitive option, other strategies such as pass-transistors that were discarded in the past because they did not fit silicon MOSFETs logic should be reconsidered. Obviously, the assessment of such alternatives requires customized CAD tools and optimization engines. The objective of this paper is to introduce a synthesis and optimization flow for pass-gate logic circuits mapped onto emerging ambipolar technologies. As main contributions we propose: 1) a novel EXNOR-based decomposition technique that fully exploits do not care conditions to generate compact logic function representations and 2) a dedicated one-pass synthesis flow where optimization and technology mapping are concurrently run on a common data structure, the reduced ordered pass-diagram. Experimental results demonstrate that the proposed flow outperforms existing synthesis tools by achieving more compact circuit representations with 8.5 × less devices and about 8 × shallower structures (on average), while still yielding lower CPU times.