Asynchrobatic logic for low-power VLSI design

• Main Author: Willingham, David John
• Published: University of Westminster 2010
• Subjects: 621.39
• Online Access: https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.520244

In this work, Asynchrobatic Logic is presented. It is a novel low-power design style that combines the energy saving benefits of asynchronous logic and adiabatic logic to produce systems whose power dissipation is reduced in several different ways. The term “Asynchrobatic” is a new word that can be used to describe these types of systems, and is derived from the concatenation and shortening of Asynchronous, Adiabatic Logic. This thesis introduces the concept and theory behind Asynchrobatic Logic. It first provides an introductory background to both underlying parent technologies (asynchronous logic and adiabatic logic). The background material continues with an explanation of a number of possible methods for designing complex data-path cells used in the adiabatic data-path. Asynchrobatic Logic is then introduced as a comparison between asynchronous and Asynchrobatic buffer chains, showing that for wide systems, it operates more efficiently. Two more-complex sub-systems are presented, firstly a layout implementation of the substitution boxes from the Twofish encryption algorithm, and secondly a front-end only (without parasitic capacitances, resistances) simulation that demonstrates a functional system capable of calculating the Greatest Common Denominator (GCD) of a pair of 16-bit unsigned integers, which under typical conditions on a 0.35μm process, executed a test vector requiring twenty-four iterations in 2.067μs with a power consumption of 3.257nW. These examples show that the concept of Asynchrobatic Logic has the potential to be used in real-world applications, and is not just theory without application. At the time of its first publication in 2004, Asynchrobatic Logic was both unique and ground-breaking, as this was the first time that consideration had been given to operating large-scale adiabatic logic in an asynchronous fashion, and the first time that Asynchronous Stepwise Charging (ASWC) had been used to drive an adiabatic data-path.