Hardware-efficient approximate multiplier architectures for media processing applications

Abstract

Purpose Multipliers that form the basic building blocks in most of the error-resilient media processing applications are computationally intensive and power-hungry modules. Therefore, improving the multiplier’s performance in terms of area, critical path delay and power has become an important research area. This paper aims to propose two improved multiplier designs based on a new approximate compressor circuit to reduce the hardware complexity at the partial product reduction stage. The proposed approximate 4:2 compressor design significantly reduces the overall hardware cost of the multiplier. The error introduced by the approximate compressor is reduced using a new technique of assigning inputs to the compressors in the partial product reduction structure. Design/methodology/approach The multiplier designs implemented using the proposed approximate 4:2 compressor are targeted for error-resilient applications. For fair comparisons, various multiplier designs, including the proposed one, are implemented in MATLAB. The quality analysis is carried out using standard images, and metrics such as structural similarity index are computed to quantify the result of proposed designs with the existing architectures. Next, Verilog gate-level designs are synthesized to compute area, delay and power to prove the efficacy of the proposed designs. Findings Exhaustive error and hardware analysis have been carried out for the existing and proposed multiplier architectures. Error analysis carried out using MATLAB proves that the proposed designs achieve better quality metrics than existing designs. Hardware results show that area, the power consumed and critical path delay are reduced up to 39.8%, 51.7% and 15.9%, respectively, compared to the existing designs. Toward the end, the proposed designs impact is quantified and compared with existing designs on real-time image sharpening and image multiplication applications. Originality/value The area, delay and power metrics of the multiplier can be improved using an approximate compressor in an error-resilient application. Accordingly, in this work, a new compressor is proposed that reduces the hardware complexity in the multiplier architecture. However, the proposed approximate compressor, while reducing the computational complexity, tends to introduce error in the multiplier. The error introduced by the approximate compressor is reduced using a new technique of assigning inputs to the compressors in the partial product reduction structure. With the help of the approximate compressor and a technique of input realignment, hardware efficient and highly accurate multiplier designs are achieved.