On the design of radix-K approximate multiplier using 2D pseudo-booth encoding

Abstract

In this paper, we propose energy-efficient unsigned approximate multipliers using the Pseudo-Booth (PB) encoding that are suitable for large dynamic-range operands thanks to leading zero remover (LZR) circuit. We have used our encoding form for both operands, so the proposed multiplier is called by two-dimensional Pseudo-Booth (2DPB) multiplier. The proposed multiplier accuracy can be adjusted by tuning the encoder radix and the truncation value. The efficiency of the proposed 2DPB multiplier has been evaluated by comparing its characteristics to those of six state-of-the-art approximate multipliers and the conventional (exact) multiplier in a TSMC-180 nm technology. The results reveal that the proposed 16-bit unsigned multiplier R8-T12, i.e., radix-8 and 12-bits truncation, provides up to 95% and 89% reductions in power-delay product (PDP) and power consumption, respectively, compared to the exact unsigned multiplier. It also provides up to 55% and 24.4% lower power-delay product (PDP), respectively, compared to the best of other approximate multipliers considered in this brief. Finally, the effectiveness of the proposed multiplier in real-life applications, including FIR filters and two image processing applications of smoothing and sharpening, is demonstrated.