Reversible and Adiabatic Computing: Energy-Efficiency Maximized - Field-Coupled Nanocomputing: Paradigms, Progress, and Perspectives - page 337

Reversible and Adiabatic Computing:
Energy-Efficiency Maximized

Ismo Hänninen 2( & ) , Hao Lu 1 , Enrique P. Blair 1 , Craig S. Lent 1 ,
and Gregory L. Snider 1

1

Center for Nano Science and Technology, University of Notre Dame,
Notre Dame, IN 46556, USA
{hlu1,eblair,lent,snider.7}@nd.edu

2

Department of Pervasive Computing, Tampere University of Technology,
P.O. Box 527, 33101 Tampere, Finland
[e-mail]

Abstract. Emerging devices promise energy-efficient computing on a massively
parallel scale, but due to the extremely high integration density the previously
insignificant dissipation due to information erasure (destruction) becomes a
prominent circuit design factor. The amount of heat generated by erasure depends
on the degree of logical reversibility of the circuits and successful adiabatic
charging. In this paper, we design an adiabatic arithmetic-logic unit to prototype
the locally-connected Bennett-clocked circuit design approach. The results
indicate one or two orders-of-magnitude energy savings in this physical circuit
implementations vs. standard static CMOS. Previous work on computer arith-
metic suggests that common hardware implementations erase much more infor-
mation than would be required by a theoretical minimal mapping of the addition
operation. A Bennett-clocked approach can reach the theoretical minimum
number of bit erasures in the binary addition, though simulations show that a
transistor technology has energy loss due to parasitic components that can exceed
the information loss heat. In this paper, we describe the relationship between
adiabatic and logically reversible circuits, and predict the potential of the arith-
metic implementations based on quantum-dot cellular automata, which enable the
full benefits of reversible, locally connected circuits to be realized.

Reversibility Addition Arithmetic Adiabatic circuit design Keywords:

1 Introduction

The computing performance of integrated circuits has been tightly connected to the
energy-efficiency of the underlying device technology, and this connection also exists
for the emerging circuits [ 1 ]. In fact, due to their inherent efficiency in conserving the
signal energy, technologies such as quantum-dot cellular automata (QCA) and
nanomagnetic logic (NML) will potentially have the dissipation due to physical state
compression and irreversibility as the limiting factors for their overall dissipation,
which in turn influences the maximum operating frequency or battery life. The com-
bination of molecular circuits and switching frequencies reaching the terahertz regime
makes

the dissipation associated with the logical and physical irreversibility a