Asynchronous switching for low-power networks-on-chip

Abstract

Asynchronous switching is proposed to achieve low power Network on Chip. Asynchronous switching reduces the power dissipation of the network if the activity factor of the data transfer between two ports αdata is less than Aαc+Bαclk. Closed form expressions for power dissipation of different network topologies are provided for both synchronous and asynchronous switching. The expressions are technology independent and are used for power estimation. Asynchronous switching is compared with synchronous switching for different network densities N/LcXLc. The area of the asynchronous switch is 50% greater than the area of the synchronous switch. However, the power dissipation of asynchronous switching decreased by up to 70.8% as compared to the power dissipation of the conventional synchronous switching for Butter-Fly Fat Tree (BFT) topology. Asynchronous switching is more efficient in CLICHE topology than in both BFT and Octagon topologies achieving higher power reduction 75.7%. Asynchronous switching becomes more efficient as technology advances and network density increases. A reduction in power dissipation reaches 82.3% for 256 IPs with the same chip size. Even with clock gating, asynchronous switching achieves significant power reduction 77.7% for 75% clock activity factor.