Automated Mapping of Clocked Logic to Quasi-Delay Insensitive Circuits

The use of computer aided design (CAD) tools has catalyzed the growth of IC design techniques. The rapid growth in transistor count for synchronous digital circuits has increased circuit complexity. This growing complexity of synchronous circuits has exposed design issues such as clock skew, increased power consumption, increased electromagnetic interference and worst case performance. The increasing number of challenges posed by synchronous designs has encouraged researchers to explore asynchronous design techniques as an alternative methodology. Asynchronous circuits do not use a global clock signal that is the primary cause of many design challenges faced by synchronous designers. It has also been shown in some designs that asynchronous circuits consumes less power, and exhibits better average case performance than synchronous circuits. Asynchronous design techniques, even with their various advantages over synchronous systems, are not widely accepted by logic designers. This is due to the shortcomings of asynchronous design methodologies, primarily, the limited availability of CAD tool support and the use of proprietary specification languages. To overcome the shortcomings of current asynchronous design techniques, this research uses a methodology for designing asynchronous circuits starting from clocked RTL design. This research extends the concepts of Phased Logic (PL) and marked graphs to quasi-delay insensitive gates (QDI) gates to create an asynchronous PL-QDI methodology. The PL methodology is easy to use as it maps conventional RTL designs into delay insensitive PL circuits using commercial CAD tools. Caltech?s QDI gates exhibit fast forward latency, but the use of Caltech?s methodology requires a user skilled in the pecurialities of the Caltech design methodology. This research uses best of Caltech?s QDI circuit methodology and the PL methodology to come up with a new asynchronous PL-QDI methodology. It also presents a synthesis algorithm that uses commercially available synchronous CAD tools to map clocked designs to PL-QDI systems. Results of this research show that third-party clocked RTL codes including intellectual property (IP) cores can be converted to asynchronous PL-QDI systems using the PL-QDI CAD tools presented in this research. This work shows how mature synchronous CAD tools can be used to design clockless circuits

Computation of Disjoint Cube Representations Using a Maximal Binate Variable Heuristic

A method for computing the Disjoint-Sum-Of-Products (DSOP) form of Boolean functions is described. The algorithm exploits the property of the most binate variable in a set of cubes to compute a DSOP form. The technique uses a minimized Sum-Of-Products (SOP) cube list as input. Experimental results comparing the size of the DSOP cube list produced by this algorithm and those produced by other methods demonstrate the efficiency of this technique and show that superior results occur in many cases for a set of benchmark functions