14 Self-Reconfigurable Constant Multiplier for FPGA JAVIER HORMIGO, Universidad de M ´ alaga GABRIEL CAFFARENA, Universidad CEU San Pablo JUAN P. OLIVER, Universidad de la Rep ´ ublica EDUARDO BOEMO, Universidad Aut´ onoma de Madrid Constant multipliers are widely used in signal processing applications to implement the multiplication of signals by a constant coefficient. However, in some applications, this coefficient remains invariable only during an interval of time, and then, its value changes to adapt to new circumstances. In this article, we present a self-reconfigurable constant multiplier suitable for LUT-based FPGAs able to reload the constant in runtime. The pipelined architecture presented is easily scalable to any multiplicand and constant sizes, for unsigned and signed representations. It can be reprogrammed in 16 clock cycles, equivalent to less than 100 ns in current FPGAs. This value is significantly smaller than FPGA partial configuration times. The presented approach is more efficient in terms of area and speed when compared to generic multipliers, achieving up to 91% area reduction and up to 102% speed improvement for the case-study circuits tested. The power consumption of the proposed multipliers are in the range of those of slice-based multipliers provided by the vendor. Categories and Subject Descriptors: B.2.4 [Arithmetic and Logic Structures]: High-Speed Arithmetic General Terms: Design, Algorithms, Performance Additional Key Words and Phrases: Constant multiplier, runtime reconfiguration, FPGA ACM Reference Format: Hormigo, J., Caffarena, G., Oliver, J. P., and Boemo, E. 2013. Self-reconfigurable constant multiplier for FPGA. ACM Trans. Reconfig. Technol. Syst. 6, 3, Article 14 (October 2013), 17 pages. DOI:http://dx.doi.org/10.1145/2490830 1. INTRODUCTION FPGA devices offer high computational power and reconfiguration capabilities that allow for complete customization and runtime adaptation of the circuit functionality. Many applications require these features in order to adjust the design to particular parameters at any given time step. Reconfiguration is a thriving field, but the long re- configuration times and storage or generation of the new bitstream are still important issues [Compton et al. 2002; Dandalis and Prasanna 2005; Kalra and Lysecky 2010]. In signal processing, it is usual that one of the multiplier operands is a constant coefficient. Thus, it is possible to optimize its hardware structure to improve area This work was partially supported by projects P07-TIC-02630 (Junta of Andaluc´ ıa), TIN2006-01078 (Min- istry of Education and Science of Spain), and USP-BS PPC05/2010 (University CEU San Pablo and Banco Santander). Authors’ addresses: J. Hormigo, Department of Computer Architecture, University of M´ alaga, M ´ alaga, Spain; email: hormigo@ac.uma.es; G. Caffarena (corresponding author), Department of Information Tech- nologies, University CEU San Pablo, Spain; email: gabriel.caffarenafernandez@ceu.es; J. P. Oliver, Facultad de Ingenier´ ıa, Universidad de la Rep ´ ublica, Uruguay; E. Boemo, Universidad Aut´ onoma de Madrid, Spain. Permission to make digital or hard copies of part or all of this work for personal or classroom use is granted without fee provided that copies are not made or distributed for profit or commercial advantage and that copies show this notice on the first page or initial screen of a display along with the full citation. Copyrights for components of this work owned by others than ACM must be honored. Abstracting with credit is per- mitted. To copy otherwise, to republish, to post on servers, to redistribute to lists, or to use any component of this work in other works requires prior specific permission and/or a fee. Permissions may be requested from Publications Dept., ACM, Inc., 2 Penn Plaza, Suite 701, New York, NY 10121-0701 USA, fax +1 (212) 869-0481, or permissions@acm.org. c  2013 ACM 1936-7406/2013/10-ART14 $15.00 DOI:http://dx.doi.org/10.1145/2490830 ACM Transactions on Reconfigurable Technology and Systems, Vol. 6, No. 3, Article 14, Publication date: October 2013.