Asynchronous quasi-delay-insensitive (QDI) circuits are known for their potentially enhanced robustness to PVT variations when compared to synchronous circuits or to bundleddata asynchronous design. They are also a good choice for highperformance circuits used to solve several real-world problems. However, it is often difficult to constrain the minimum performance for QDI circuits. Thus, enhancing the synthesis quality for QDI design is a justifiable effort, especially in rising application fields, such as the Internet of Things and Artificial Intelligence. This work proposes Pulsar, a method based on the extension of SDDS-NCL, a previously proposed asynchronous QDI template and design flow. Pulsar brings four original contributions: (i) two new models for components used to as sequential barriers;(ii) a new model for half buffer pipelines, half-buffer channel network (HBCN); (iii) a linear programming formulation to define a circuit cycle time constraint; (iv) a design flow that enables automating the process to design sequential SDDS-NCL circuits. Experiments comparing synthesis results with Pulsar of a 6-stage, multiply-accumulate (MAC) show that it can guarantee a maximum cycle time of 3.2 ns, while the original Unclesynthesised circuit without logic optimisation leads to timing violations at a 6 ns constraint.
Asynchronous quasi-delay-insensitive circuits are known for their robustness against variations, but their widespread use has been prey to the absence of adequate design methods and lack of design and verification tools. The recently proposed Pulsar flow enables the design and optimisation of quasi-delay-insensitive circuits using conventional EDA tools, enhanced by adequate libraries, methods and models. Pulsar enables designers to naturally trade performance for power or area, whenever there is slack in timing budgets. However, Pulsar lacked an automated dual-rail expansion method to support its operation, requiring that designers manually develop a timing model as input to the computation of asynchronous cycle time constraints. This paper proposes and describes the features of a frontend for Pulsar. Pulsar-F, the new flow version can be used as a push-button design tool for asynchronous QDI circuits. Pulsar-F adds the following features to Pulsar: (i) an RTL-based design capture method; (ii) a heuristic, timing-driven singlerail pre-synthesis process using commercial EDA tools; (iii) a dual-rail expansion technique with fine-grain acknowledgement network generation; (iv) a tool that automates the computation of the Hal-Buffer Channel Network (HBCN) graph-based timing model for pre-synthesised circuits and derives a set of timing constraints for it. Experiments show that Pulsar-F improves Pulsar to further aid asynchronous designers to trade off power, area and performance.
Internet of Things devices require innovative power efficient design techniques that ensure correct operation in harsh environments, where using synchronous design can be challenging. The timing sign-off of synchronous circuits requires analysis and optimisation under multiple corners and operating modes. Considering that energy efficient circuits demand dynamic voltage ranges and harsh environments impose significant variations, design sign-off may become prohibitively expensive. An alternative is quasi-delay-insensitive asynchronous design, which presents robustness against timing variations, simplifying timing sign-off. This paper leverages recent developments in asynchronous circuits design automation to achieve higher degrees of energy efficiency using voltage scaling, while ensuring solid robustness to variability.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.