Asynchronous pipeline controller based on early acknowledgement protocol

A new asynchronous pipeline controller based on early acknowledgement protocol is proposed. The early acknowledgement protocol indicates acknowledgment by the falling edge of the acknowledgment signal, and thus, it can hide the overhead caused by a resetting phase of the handshake cycle. Advantage of employing the early acknowledgement protocol in a pipeline controller is demonstrated by comparing its performance with a very high-speed 2-phase pipeline controller and an ordinary 4-phase controller. The simulation results obtained in our experiment show that in a linear pipeline case with processing elements in-between the stages, our controller has performance comparable to the 2-phase controller, and outperforms the ordinarily 4-phase controller. Moreover, we have obtained interesting results in the case of a nonlinear pipeline with a Conditional Branch operation. In this case, a 2-phase controller needs to have a little complicated mechanism to handle the 2-phase operation for selecting a path, while our controller is trivial in construction similar to the ordinary 4-phase protocol controller. Due to such simplicity of the implementation, our controller has a slightly better performance compared to the 2-phase controller when each stage has a processing element.