Synthesis of QDI AFSMs from XBM specifications

Abstract

Due to the increasing demand for mobile devices, the search for ultra-low-power projects is becoming a priority. One technique that allows a strong reduction of circuits dissipated power is the sub-threshold voltage operation, but it leads to some drawbacks. The QDI (Quasi Delay Insensitive) asynchronous circuits class show to be an interesting solution to these problems, when presented in synchronous circuits and in CMOS-UDSM (Ultra Deep Sub-Micron) technology. Asynchronous finite state machines (AFSMs) are important components in an asynchronous system. This paper proposes a new architecture for QDI_AFSMs. These machines are described in the extended burst-mode (XBM) specification and synthesized in a very simple way. The QDI_XBM_AFSMs are implemented in the dual-rail style, using NCL (NULL Convention Logic) gates. The resulting AFSMs are QDI, so they can operate with sub-threshold voltage. The architecture is presented through the case study and the obtained QDI_XBM_AFSM shows interesting results, when compared with two QDI controller of the literature, which are based on basic gates and C element.