2nd order adiabatic computation with 2N-2P and 2N-2N2P logic circuits
A. Kramer, John S. Denker, Barry Flower, John P. Moroney · 1995
Recent advances in compact, practical adiabatic computing circuits which demonstrate signi cant energy savings have renewed interest in using such techniques in lowpower systems.Several recently introduced circuits for adiabatic computing make use of diodes in a way which reduces switching energy from O(CVdd 2 ) in the nonadiabatic (ie: standard CMOS) case, to O(CV ddV t).These circuits provide an energy savings of at most one order of V dd=V t.This paper introduces a new class of adiabatic computing circuits which oer several advantages over existing approaches, the primary one being that, because no diodes are used, switching energy can be reduced to an energy oor of O(CVt 2 ).These second order adiabatic computing circuits provide an energy savings of as much a s O ( V dd=V t 2 ) o v er conventional CMOS.Additional advantages of the proposed circuits include the fact that, in comparison to most compact adiabatic circuits which h a v e oating output levels over the entire data valid time, these new circuits have nonoating output levels over most of the data valid time.This is important for restoring logic levels and minimizing problems with crosstalk.The proposed circuits have been simulated and demonstrate adiabatic power savings compared to standard CMOS circuits over an operating frequency range from 1MHz to 100MHz of as much a s a factor of 3. One circuit topology has been fabricated and tested and operates properly at up to 100MHz, the maximum speed which could be tested.Power measurements on the functioning circuit are in progress and preliminary results demonstrate adiabatic power-vs-frequency behavior.These second order adiabatic computing circuits provide an attractive alternative t o a c hieve adiabatic power savings without suering from many o f t h e limitations of alternative approaches and without costing much more either in terms of complexity or size.