Asymptotically zero energy computing using split-level charge recovery logic

The dynamic power requirement of CMOS circuits is rapidly becoming a major concern in the design of personal information systems and large computers. In this work we present a number of new CMOS logic families, Charge Recovery Logic (CRL) as well as the much improved Split-Level Charge Recovery Logic (SCRL), within which the transfer of charge between the nodes occurs quasistatically. Operating quasistatically, these logic families have an energy dissipation that drops linearly with operating frequency, i.e., their power consumption drops quadratically with operating frequency as opposed to the linear drop of conventional CMOS. The circuit techniques in these new families rely on constructing an explicitly reversible pipelined logic gate, where the information necessary to recover the energy used to compute a value is provided by computing its logical inverse. Information necessary to uncompute the inverse is available from the subsequent inverse logic stage. We demonstrate the low energy operation of SCRL by presenting the results from the testing of the rst fully quasistatic 8 8 multiplier chip (SCRL-1) employing SCRL circuit techniques. Acknowledgments In consulting with Tom Knight throughout this work, many a times I was the recipient of the following advice \... of course you can do it that way, but if I was doing it I would..." and many a times I went my own way. On reeection, I wish that for the most part, I had not. When it comes to technical intuition of the kind that usually turns out to be true, Tom Knight seems to have an enviable supply. I'm thankful for having worked with him technically and grateful for having known him personally. I wish to thank Gregory Papodopoulos and Kim Molvig for their commitment and support of this work. I would also like to thank members of toms-knights group including Sir Philip Alvelda, Sir Mike Bolotski, Sir Andre Dehon and Sir Tom Simon for their instrumental help during the design of SCRL-1. Special thanks to Andy Boughton and Jack Costanza for their generosity, and friendship during the testing of SCRL-1 chip and throughout my hacking days at MIT.