The general objective of our work is to develop methods to reduce the energy consumption of arithmetic modules while maintaining the delay unchanged and keeping the increase in the area to a minimum. Here, we present techniques for dividers and square root units realized in CMOS technology. The energy dissipation reduction is carried out at different levels of abstraction: from the algorithm level down to the implementation, or gate, level. We describe the use of techniques such as switching-off not active blocks, retiming, dual voltage, and equalizing the paths to reduce glitches. Also, we describe modifications in the on-the-fly conversion and rounding algorithm and in the redundant representation of the residual in order to reduce the energy dissipation. The techniques and modifications mentioned above are applied to several division and square root schemes, realized with static CMOS standard cells, for which a reduction in the energy dissipation of about 40 percent is obtained with respect to the standard implementation optimized for minimum delay. This reduction is expected to be even larger if low-voltage gates, for dual voltage implementation, are available.

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Alberto Nannarelli ( alberto@ece.uci.edu )