Asynchronous QDI circuit synthesis from signal transition protocols

Asynchronous circuits are promising in resolving the emerging issue of process variation and high synchronization power consumption. Among various asynchronous delay models, quasi-delay insensitive (QDI) model is the most robust and yet practical one due to its relaxed timing assumption. However, automatic synthesis of QDI circuits from signal transition graph (STG) protocol specification has not yet been proposed, despite the fact that algorithms synthesizing circuits under other delay models do exist. In this paper we propose the first algorithm synthesizing protocols specified in STGs into QDI circuits by analyzing STG structures without utilizing state graph assignment techniques. Furthermore, an optimization technique is proposed to simplify QDI circuits. In our synthesis algorithm, the state explosion issue is avoided, and restrictions on STGs are relaxed. Case studies on Advanced Microcontroller Bus Architecture (AMBA) and other protocols indicate the feasibility of our method.