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Issue No. 08 - Aug. (2017 vol. 66)
ISSN: 0018-9340
pp: 1435-1441
Weiqiang Liu , College of Electronic Information and Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing, Jiangsu, China
Liangyu Qian , College of Electronic Information and Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing, Jiangsu, China
Chenghua Wang , College of Electronic Information and Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing, Jiangsu, China
Honglan Jiang , Department of Electrical and Computer Engineering, University of Alberta, Edmonton, AB, Canada
Jie Han , Department of Electrical and Computer Engineering, University of Alberta, Edmonton, AB, Canada
Fabrizio Lombardi , Department of Electrical and Computer Engineering, Northeastern University, Boston, MA
ABSTRACT
Approximate computing is an attractive design methodology to achieve low power, high performance (low delay) and reduced circuit complexity by relaxing the requirement of accuracy. In this paper, approximate Booth multipliers are designed based on approximate radix-4 modified Booth encoding (MBE) algorithms and a regular partial product array that employs an approximate Wallace tree. Two approximate Booth encoders are proposed and analyzed for error-tolerant computing. The error characteristics are analyzed with respect to the so-called approximation factor that is related to the inexact bit width of the Booth multipliers. Simulation results at 45 nm feature size in CMOS for delay, area and power consumption are also provided. The results show that the proposed 16-bit approximate radix-4 Booth multipliers with approximate factors of 12 and 14 are more accurate than existing approximate Booth multipliers with moderate power consumption. The proposed R4ABM2 multiplier with an approximation factor of 14 is the most efficient design when considering both power-delay product and the error metric NMED. Case studies for image processing show the validity of the proposed approximate radix-4 Booth multipliers.
INDEX TERMS
Logic gates, Delays, Image coding, Encoding, Power demand, Adders,Radix-4 multiplier, booth encoder, approximate computing, low power
CITATION
Weiqiang Liu, Liangyu Qian, Chenghua Wang, Honglan Jiang, Jie Han, Fabrizio Lombardi, "Design of Approximate Radix-4 Booth Multipliers for Error-Tolerant Computing", IEEE Transactions on Computers, vol. 66, no. , pp. 1435-1441, Aug. 2017, doi:10.1109/TC.2017.2672976
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