NCL+: Return-to-one Null Convention Logic

Asynchronous paradigms are a way to deal with hard problems in newer technologies. Among the templates for ensuring efficient asynchronous design, Null Convention Logic (NCL) appears as a fast and relatively low area and power option, enabling semi-custom design. This work proposes a new asynchronous logic template, NCL+, which is a modification of NCL to support the return-to-one protocol. A basic library of NCL+ standard-cells, with different driving strengths enables comparison between NCL and NCL+. While no significant differences in area arise, results suggest that a trade-off of power versus forward propagation delay exists. Accordingly, NCL+ provides more power efficiency and NCL provides smaller forward propagation delays.