Snake: An asynchronous pipeline for ultra-low-power applications

Voltage scaling is an effective technique for ultra-low-power applications. However, PVT variation degrades the robust of traditional synchronous pipelines severely when voltage scales into the sub-threshold region. In this paper, we propose a register-based bundled-data asynchronous pipeline that can operate robustly in sub-threshold, called Snake. By looping the match delay line, the Snake halves the design overhead compared to other asynchronous pipelines. We also propose a practical asynchronous design methodology which is compatible with commercial EDA and needs only a few modifications to synchronous design flow. Monte-Carlo SPICE simulation shows that the pipelined multiplier applying the proposed techniques operates stably in 0.2V and achieves minimum power 1.3nW in 0.2V, minimum energy 1.07 pJ per cycle in 0.3V. It provides 6.7 times superiority over synchronous baseline design with 22% area overhead. Comparison with other works in the state of art shows the proposed techniques are quite competitive.