Low-power pipelined crypto-core using a backup flip-flop

Abstract

With increasing clock frequencies, power-aware computing has become a critical concern in the VLSI design. One of the most effective and widely used method for lowering the power is DVS (Dynamic Voltage Scaling), which is the basic idea behind making low-power pipeline. Total power consumed by the system consists of dynamic power and leakage power. They both depend on the supply voltage, as they decrease with a decrement in supply voltage. But lower supply voltage causes more delays at the gate level, as there is less amount of voltage to charge the output capacitance of a gate. These delays can cause timing violations in the critical path. So, if the supply voltage of the system could be reduced somehow without affecting the overall functionality of the system, great power saving can be achieved. Usual DVS techniques need to have margin for process and temperature variations or any local variations. These voltage margins make the design less efficient in terms of power. Backup flip-flop can be used for the critical path, which operates on the different clock, delayed by some specific amount of delay. It covers the effect of voltage reduction as well as process and temperature variations with all local variation effects, which can affect delay in any manner. If there is any error, it needs to be corrected for a correct functionality of the system. Error correction mechanism and the architectural overview of AES crypto-core is also discussed, as it is the chosen design on which this concept would be implemented. Similar concept has been successfully tried out on Alpha processor with satisfactory result. All the simulations shown are post-synthesis or post-route simulations so that they reflect the approximated delays and timing checks of logical gates and interconnects. Simulations and synthesis were performed using Cadence NC-Launch and Encounter RTL Compiler respectively. ’Nangate Opencell Library’ with 45nm technology was used for the synthesis.