Engineering Science and Technology, an International Journal (Jun 2017)
Asynchronous carry select adders
Abstract
This paper discusses the standard cell based designs of asynchronous carry select adders (CSLAs) corresponding to strong-indication, weak-indication, and early output timing regimes realized using a delay-insensitive dual-rail code for data representation and processing, and a 4-phase return-to-zero protocol for handshaking. Many 32-bit asynchronous CSLAs corresponding to a uniform input partition viz. 8-8-8-8 and a non-uniform input partition viz. 8-7-6-4-3-2-2 were considered for implementation and comparison. All the asynchronous CSLAs were physically realized in semi-custom ASIC design style using a 32/28 nm CMOS process technology. The simulation results show that the 32-bit early output asynchronous CSLA based on the uniform input partition (8-8-8-8) enables optimized data path latency, area occupancy, and average power dissipation compared to the rest.
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