A zero-time-overhead asynchronous four-phase controller

Asynchronous single-rail datapath implementations turn out to be superior to the dual-rail implementations in some dimensions; they consume less energy and require less circuit area. However, there still exist area overhead of matched delay elements and control time overhead of the four-phase handshake protocol. In this paper, we introduce a new interface so that such time overhead can be reused as a part of the matched delay. Consequently, the time overhead can be zero, and the amount of components used for composing the matched delay can be dramatically reduced. The larger the control time overhead is, the smaller the delay chain becomes. The full performance and low-power advantages of asynchronous circuits can be obtained. We demonstrate this on a single-rail differential equation solver.