Design of Approximate Unsigned Integer Non-restoring Divider for Inexact Computing

Abstract

This paper proposes several approximate divider designs; two different levels of approximation (cell and array levels) are investigated for non-restoring division. Three approximate subtractor cells are proposed and designed for the basic subtraction; these cells mitigate accuracy in subtraction with other metrics, such as circuit complexity and power dissipation. At array level, by considering the exact cells, both replacement and truncation schemes are introduced for approximate array divider design. A comprehensive evaluation of approximation at both cell and divider level is pursued. Different circuit metrics including complexity and power dissipation are evaluated by HSPICE simulation. Mean error distance (MED), normalized error distance (NED) and MED-power product (MPP) are provided to substantiate the accuracy and power trade-off of inexact computing. Different applications in image processing are investigated by utilizing the proposed approximate arithmetic circuits.